Structural Engineering of Anode Materials for Low-Temperature Lithium-Ion Batteries:Mechanisms,Strategies,and Prospects

The severe degradation of electrochemical performance for lithium-ion batteries(LIBs)at low temperatures poses a significant challenge to their practical applications.Consequently,extensive efforts have been contributed to explore novel anode materials with high electronic conductivity and rapid Li^(+)diffusion kinetics for achieving favorable low-temperature performance of LIBs.Herein,we try to review the recent reports on the synthesis and characterizations of low-temperature anode materials.First,we summarize the underlying mechanisms responsible for the performance degradation of anode materials at subzero temperatures.Second,detailed discussions concerning the key pathways(boosting electronic conductivity,enhancing Li^(+)diffusion kinetics,and inhibiting lithium dendrite)for improving the low-temperature performance of anode materials are presented.Third,several commonly used low-temperature anode materials are briefly introduced.Fourth,recent progress in the engineering of these low-temperature anode materials is summarized in terms of structural design,morphology control,surface&interface modifications,and multiphase materials.Finally,the challenges that remain to be solved in the field of low-temperature anode materials are discussed.This review was organized to offer valuable insights and guidance for next-generation LIBs with excellent low-temperature electrochemical performance.

Low-temperature characteristicsof rubbers and performance testsof type 120 emergencyvalve diaphragms

Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.

Boosting oxygen reduction activity and CO_(2) resistance on bismuth ferrite-based perovskite cathode for low-temperature solid oxide fuel cells below 600℃

Developing efficient and stable cathodes for low-temperature solid oxide fuel cells(LT-SOFCs) is of great importance for the practical commercialization.Herein,we propose a series of Sm-modified Bi_(0.7-x)Sm_xSr_(0.3)FeO_(3-δ) perovskites as highly-active catalysts for LT-SOFCs.Sm doping can significantly enhance the electrocata lytic activity and chemical stability of cathode.At 600℃,Bi_(0.675)Sm_(0.025)Sr_(0.3)FeO_(3-δ)(BSSF25) cathode has been found to be the optimum composition with a polarization resistance of 0.098 Ω cm^2,which is only around 22.8% of Bi_(0.7)Sr_(0.3)FeO_(3-δ)(BSF).A full cell utilizing BSSF25 displays an exceptional output density of 790 mW cm^(-2),which can operate continuously over100 h without obvious degradation.The remarkable electrochemical performance observed can be attributed to the improved O_(2) transport kinetics,superior surface oxygen adsorption capacity,as well as O_(2)p band centers in close proximity to the Fermi level.Moreover,larger average bonding energy(ABE) and the presence of highly acidic Bi,Sm,and Fe ions restrict the adsorption of CO_(2) on the cathode surface,resulting in excellent CO_(2) resistivity.This work provides valuable guidance for systematic design of efficient and durable catalysts for LT-SOFCs.

Anisotropic etching mechanisms of 4H-SiC:Experimental and first-principles insights

Molten-alkali etching has been widely used to reveal dislocations in 4H silicon carbide(4H-SiC),which has promoted the identification and statistics of dislocation density in 4H-SiC single crystals.However,the etching mechanism of 4H-SiC is limited misunderstood.In this letter,we reveal the anisotropic etching mechanism of the Si face and C face of 4H-SiC by combining molten-KOH etching,X-ray photoelectron spectroscopy(XPS)and first-principles investigations.The activation energies for the molten-KOH etching of the C face and Si face of 4H-SiC are calculated to be 25.09 and 35.75 kcal/mol,respectively.The molten-KOH etching rate of the C face is higher than the Si face.Combining XPS analysis and first-principles calculations,we find that the molten-KOH etching of 4H-SiC is proceeded by the cycling of the oxidation of 4H-SiC by the dissolved oxygen and the removal of oxides by molten KOH.The faster etching rate of the C face is caused by the fact that the oxides on the C face are unstable,and easier to be removed with molten alkali,rather than the C face being easier to be oxidized.

The etching strategy of zinc anode to enable high performance zinc-ion batteries

Zinc-ion batteries(ZIBs)are considered to be one of the most promising candidates to replace lithium-ion batteries(LIBs)due to the high theoretical capacity,low cost and intrinsic safety.However,zinc dendrites,hydrogen evolution reaction,surface passivation and other side reactions will inevitably occur during the charging and discharging process of Zn anode,which will seriously affect the cycle stability of the battery and hinder its practical application.The etching strategy of Zn anode has attracted wide attention because of its simple operation and broad commercial prospects,and the etched Zn anode can effectively improve its electrochemical performance.However,there is no comprehensive review of the etching strategy of Zn anode.This review first summarizes the challenges faced by Zn anode,then puts forward the etching mechanisms and properties of acid,salt and other etchants.Finally,based on the above discussion,the challenges and opportunities of Zn anode etching strategy are proposed.

Etching of quartz crystals in liquid phase environment:A review

Quartz crystals are the most widely used material in resonant sensors,owing to their excellent piezoelectric and mechanical properties.With the development of portable and wearable devices,higher processing efficiency and geometrical precision are required.Wet etching has been proven to be the most efficient etching method for large-scale production of quartz devices,and many wet etching approaches have been developed over the years.However,until now,there has been no systematic review of quartz crystal etching in liquid phase environments.Therefore,this article provides a comprehensive review of the development of wet etching processes and the achievements of the latest research in thisfield,covering conventional wet etching,additive etching,laser-induced backside wet etching,electrochemical etching,and electrochemical discharge machining.For each technique,a brief overview of its characteristics is provided,associated problems are described,and possible solutions are discussed.This review should provide an essential reference and guidance for the future development of processing strategies for the manufacture of quartz crystal devices.

Etching Mechanism of Ti_(3)C_(2)Cl_(2) MXene Phases by CuCl_(2)-Lewis Molten Salt Method

We described a method for obtaining fluorine-free Ti_(3)C_(2)Cl_(2)MXene phases by melting copper in CuCl_(2)instead of aluminum in Ti_(3)AlC_(2).XRD results show that when molten salt CuCl_(2)etches Ti_(3)AlC_(2),it forms an intermediate product Ti_(3)CuC_(2),and then reacts with Ti_(3)CuC_(2)to obtain Ti_(3)C_(2)Cl_(2).The reaction of Ti_(3)AlC_(2)and CuCl_(2)at a temperature of 800℃for 2 h to obtain Ti_(3)C_(2)Cl_(2)with an optimal lamellar structure is shown in SEM results.The pseudopotential plane-wave(PP-PW)method is used to calculate on the electronic structure.The etching mechanism is investigated by the total energies of each substance.The chemical reaction of Ti_(3)AlC_(2)and CuCl_(2)will first become Ti_(3)CuC_(2)and Cu,and then become Ti_(3)C_(2)Cl_(2)during the Lewis acid etching process,which are consistent with the experimental results.

Remote plasma enhanced cyclic etching of a cyclosiloxane polymer thin film

The continuous evolution of chip manufacturing demands the development of materials with ultra-low dielectric constants.With advantageous dielectric and mechanical properties,initiated chemical vapor deposited(iCVD)poly(1,3,5-trimethyl-1,3,5-trivinyl cyclotrisiloxane)(pV3D3)emerges as a promising candidate.However,previous works have not explored etching for this cyclosiloxane polymer thin film,which is indispensable for potential applications to the back-end-of-line fabrication.Here,we developed an etching process utilizing O2/Ar remote plasma for cyclic removal of iCVD pV3D3 thin film at sub-nanometer scale.We employed in-situ quartz crystal microbalance to investigate the process parameters including the plasma power,plasma duration and O2 flow rate.X-ray photoelectron spectroscopy and cross-sectional microscopy reveal the formation of an oxidized skin layer during the etching process.This skin layer further substantiates an etching mechanism driven by surface oxidation and sputtering.Additionally,this oxidized skin layer leads to improved elastic modulus and hardness and acts as a barrier layer for protecting the bottom cyclosiloxane polymer from further oxidation.

Advances in sodium-ion batteries at low-temperature: Challenges and strategies

With the continuing boost in the demand for energy storage,there is an increasing requirement for batteries to be capable of operation in extreme environmental conditions.Sodium-ion batteries(SIBs) have emerged as a highly promising energy storage solution due to their promising performance over a wide range of temperatures and the abundance of sodium resources in the earth's crust.Compared to lithiumion batteries(LIBs),although sodium ions possess a larger ionic radius,they are more easily desolvated than lithium ions.Fu rthermore,SIBs have a smaller Stokes radius than lithium ions,resulting in improved sodium-ion mobility in the electrolyte.Nevertheless,SIBs demonstrate a significant decrease in performance at low temperatures(LT),which constrains their operation in harsh weather conditions.Despite the increasing interest in SIBs,there is a notable scarcity of research focusing specifically on their mechanism under LT conditions.This review explores recent research that considers the thermal tolerance of SIBs from an inner chemistry process perspective,spanning a wide temperature spectrum(-70 to100℃),particularly at LT conditions.In addition,the enhancement of electrochemical performance in LT SIBs is based on improvements in reaction kinetics and cycling stability achieved through the utilization of effective electrode materials and electrolyte components.Furthermore,the safety concerns associated with SIBs are addressed and effective strategies are proposed for mitigating these issues.Finally,prospects conducted to extend the environmental frontiers of commercial SIBs are discussed mainly from three viewpoints including innovations in materials,development and research of relevant theoretical mechanisms,and intelligent safety management system establishment for larger-scale energy storage SIBs.

Temperature inversion enables superior stability for low-temperature Zn-ion batteries

It is challenging for aqueous Zn-ion batteries(ZIBs)to achieve comparable low-temperature(low-T)performance due to the easy-frozen electrolyte and severe Zn dendrites.Herein,an aqueous electrolyte with a low freezing point and high ionic conductivity is proposed.Combined with molecular dynamics simulation and multi-scale interface analysis(time of flight secondary ion mass spectrometry threedimensional mapping and in-situ electrochemical impedance spectroscopy method),the temperature independence of the V_(2)O_(5)cathode and Zn anode is observed to be opposite.Surprisingly,dominated by the solvent structure of the designed electrolyte at low temperatures,vanadium dissolution/shuttle is significantly inhibited,and the zinc dendrites caused by this electrochemical crosstalk are greatly relieved,thus showing an abnormal temperature inversion effect.Through the disclosure and improvement of the above phenomena,the designed Zn||V_(2)O_(5)full cell delivers superior low-T performance,maintaining almost 99%capacity retention after 9500 cycles(working more than 2500 h)at-20°C.This work proposes a kind of electrolyte suitable for low-T ZIBs and reveals the inverse temperature dependence of the Zn anode,which might offer a novel perspective for the investigation of low-T aqueous battery systems.

Impact of Low-temperature Storage on Volatile Flavor Compounds in Prepared Pork Products

[Objectives]This study was conducted to explore the dynamic changes of volatile flavor compounds in prepared pork during storage at different low-temperature conditions.[Methods]Prepared pork was stored at 4,-4 and-18℃.The volatile flavor compounds of prepared pork were determined by solid-phase microextraction-gas chromatography-mass spectrometry(SPME-GC-MS)at days 0,7,14,21 and 28,and relative odor activity value(OAV),principal component analysis(PCA)and cluster analysis(CA)were combined to analyze changes in volatile flavor compounds of prepared pork during storage.[Results]The total number of volatile flavor compounds gradually decreased with the prolongation of the storage period,and OAV analysis identified 22 key flavor compounds(OAV≥1).The results of PCA and CA showed that 2-methyl-1-butanol,1-octen-3-ol,linalool,cineole,hexanal and nonanal were the main key flavor components,and the degree of flavor degradation was low under both superchilling and freezing conditions.After 28 days of storage,the alcohol content in the chilling group was significantly higher than other two groups,and the overall content of volatile flavor compounds was also significantly higher than other two groups,indicating that the-4℃chilling storage was more favorable for maintaining the overall flavor of prepared pork.[Conclusions]This study provides a theoretical basis for finding a better storage method for prepared meat products.

Enhancing performance of low-temperature processed CsPbI2Br all-inorganic perovskite solar cells using polyethylene oxide-modified TiO_(2)

CsPbX_(3)-based(X=I,Br,Cl)inorganic perovskite solar cells(PSCs)prepared by low-temperature process have attracted much attention because of their low cost and excellent thermal stability.However,the high trap state density and serious charge recombination between low-temperature processed TiO_(2)film and inorganic perovskite layer interface seriously restrict the performance of all-inorganic PSCs.Here a thin polyethylene oxide(PEO)layer is employed to modify TiO_(2)film to passivate traps and promote carrier collection.The impacts of PEO layer on microstructure and photoelectric characteristics of TiO_(2)film and related devices are systematically studied.Characterization results suggest that PEO modification can reduce the surface roughness of TiO_(2)film,decrease its average surface potential,and passivate trap states.At optimal conditions,the champion efficiency of CsPbI_(2)Br PSCs with PEO-modified TiO_(2)(PEO-PSCs)has been improved to 11.24%from 9.03%of reference PSCs.Moreover,the hysteresis behavior and charge recombination have been suppressed in PEO-PSCs.

Ca and Sr co-doping induced oxygen vacancies in 3DOM La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts for boosting low-temperature oxidative coupling of methane

It is urgent to develop catalysts with application potential for oxidative coupling of methane(OCM)at relatively lower temperature.Herein,three-dimensional ordered macro porous(3 DOM)La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)(A_(2)B_(2)O_(7)-type)catalysts with disordered defective cubic fluorite phased structure were successfully prepared by a colloidal crystal template method.3DOM structure promotes the accessibility of the gaseous reactants(O2and CH4)to the active sites.The co-doping of Ca and Sr ions in La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts improved the formation of oxygen vacancies,thereby leading to increased density of surface-active oxygen species(O_(2)^(-))for the activation of CH4and the formation of C2products(C2H6and C2H4).3DOM La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts exhibit high catalytic activity for OCM at low temperature.3DOM La1.7Sr0.3Ce1.7Ca0.3O7-δcatalyst with the highest density of O_(2)^(-)species exhibited the highest catalytic activity for low-temperature OCM,i.e.,its CH4conversion,selectivity and yield of C2products at 650℃are 32.2%,66.1%and 21.3%,respectively.The mechanism was proposed that the increase in surface oxygen vacancies induced by the co-doping of Ca and Sr ions boosts the key step of C-H bond breaking and C-C bond coupling in catalyzing low-temperature OCM.It is meaningful for the development of the low-temperature and high-efficient catalysts for OCM reaction in practical application.

Mechanism of K/Ni Etching for Biochar-H_(2)O Gasification

Biomass-H_(2)O gasification is a complex thermochemical reaction,including three processes of volatile removal:homogeneous/heterogeneous reforming,biochar gasification and etching.The rate-determining step is biochar-H_(2)O gasification and etching so the DFT is carried out to see the catalytic role of different metal elements(K/Ni)in the zigzag biochar model.The calculation results show that the gasification of biochar-H_(2)O needs to go through four processes:dissociative adsorption of water,hydrogen transfer(hydrogen desorption,hydrogen atom transfer),carbon dissolution and CO desorption.The energy barrier indicated that the most significant step in reducing the activation energy of K is reflected in the hydrogen transfer step,which is reduced from 374.14 kJ/mol to 152.41 kJ/mol;the catalytic effect of Ni is mainly reflected in the carbon dissolution step,which is reduced from 122.34 kJ/mol to 84.8 kJ/mol.The existence of K causes the edge to have a stronger attraction to H and does not destroy theπbonds of biochar molecules.The destruction ofπbonds is mainly due to the role of H free radicals,while the destruction ofπbonds will lead to easier C-C bond rupture.Ni shows a strong attraction to O in OH,which forms strong Ni-O chemical bonds.Ni can also destroy the aromatic structure directly,making the gasification easier to happen.This study explored the catalytic mechanism of K/Ni on the biochar-H_(2)O gasification at the molecular level and looked forward to the potential synergy of K/Ni,laying a foundation for experimental research and catalyst design.

In situ synthesis of SnPS_(3)/Ti_(3)C_(2)T_(x) hybrid anode via molten salt etching method for superior sodium-ion batteries

Recently,SnPS_(3) has gained attention as an impressive sodium-ion battery anode material because of its significant theoretical specific capacity derived from the conversion-alloying reaction mechanism.Nevertheless,its practical applicability is restricted by insufficient rate ability,and severe capacity loss due to inadequate electrical conductivity and dramatic volume expansion.Inspired by the electrochemical enhancement effect of MXene substrates and the innovative Lewis acidic etching for MXene preparation,SnPS_(3)/Ti_(3)C_(2)T_(x) MXene(T=-Cl and-O) is constructed by synchronously phospho-sulfurizing Sn/Ti_(3)C_(2)T_(x) precursor.Benefiting from the boosted Na^(+) diffusion and electron transfer rates,as well as the mitigated stress expansion,the synthesized SnPS_(3/)Ti_(3)C_(2)T_(x) composite demonstrates enhanced rate capability(647 mA h g^(-1) at 10 A g^(-1)) alongside satisfactory long-term cycling stability(capacity retention of 94.6% after 2000 cycles at 5 A g^(-1)).Importantly,the assembled sodium-ion full cell delivers an impressive capacity retention of 97.7% after undergoing 1500 cycles at 2 A g^(-1).Moreover,the sodium storage mechanism of the SnPS_(3/)Ti_(3)C_(2)T_(x) electrode is elucidated through in-situ and ex-situ characterizations.This work proposes a novel approach to ameliorate the energy storage performance of thiophosphites by facile in-situ construction of composites with MXene.

Recent Advances and Perspectives of Lewis Acidic Etching Route:An Emerging Preparation Strategy for MXenes

Since the discovery in 2011,MXenes have become the rising star in the field of two-dimensional materials.Benefiting from the metallic-level conductivity,large and adjustable gallery spacing,low ion diffusion barrier,rich surface chemistry,superior mechanical strength,MXenes exhibit great application prospects in energy storage and conversion,sensors,optoelectronics,electromagnetic interference shielding and biomedicine.Nevertheless,two issues seriously deteriorate the further development of MXenes.One is the high experimental risk of common preparation methods such as HF etching,and the other is the difficulty in obtaining MXenes with controllable surface groups.Recently,Lewis acidic etching,as a brand-new preparation strategy for MXenes,has attracted intensive attention due to its high safety and the ability to endow MXenes with uniform terminations.However,a comprehensive review of Lewis acidic etching method has not been reported yet.Herein,we first introduce the Lewis acidic etching from the following four aspects:etching mechanism,terminations regulation,in-situ formed metals and delamination of multi-layered MXenes.Further,the applications of MXenes and MXene-based hybrids obtained by Lewis acidic etching route in energy storage and conversion,sensors and microwave absorption are carefully summarized.Finally,some challenges and opportunities of Lewis acidic etching strategy are also presented.

Perspective on low-temperature electrolytes for LiFePO 4-based lithium-ion batteries

The olivine-type lithium iron phosphate(LiFePO_(4))cathode material is promising and widely used as a high-performance lithium-ion battery cathode material in commercial batteries due to its low cost,environmental friendliness,and high safety.At present,LiFePO_(4)/C sec-ondary batteries are widely used for electronic products,automotive power batteries,and other occasion-related applications with good thermal stability,stable cycle performance,and low room-temperature self-discharge rate.However,LiFePO_(4)-based battery applications are seriously limited when they are operated in a cold climate.This outcome is due to a considerable decrease in Li+transport capabilities within the elec-trode,particularly leading to a dramatic decrease in the electrochemical capacity and power performance of the electrolyte.Therefore,the design of low-temperature electrolytes is important for the further commercial application of LiFePO_(4) batteries.This paper reviews the key factors for the poor low-temperature performance of LiFePO_(4)-based batteries and the research progress of low-temperature electrolytes.Spe-cial attention is paid to electrolyte components,including lithium salts,cosolvents,additives,and the development of new electrolytes.The factors affecting the anode are also analyzed.Finally,according to the current research progress,some viewpoints are summarized to provide suitable modification methods and research suggestions for improving the practicability of LiFePO_(4)/C commercial batteries at low temperat-ures in the future.

Etching‑Induced Surface Reconstruction of NiMoO_(4) for Oxygen Evolution Reaction

Rational reconstruction of oxygen evolution reaction(OER)precatalysts and performance index of OER catalysts are crucial but still challenging for universal water electrolysis.Herein,we develop a double-cation etching strategy to tailor the electronic structure of NiMoO_(4),where the prepared NiMoO_(4) nanorods etched by H_(2)O_(2) reconstruct their surface with abundant cation deficiencies and lattice distortion.Calculation results reveal that the double cation deficiencies can make the upshift of d-band center for Ni atoms and the active sites with better oxygen adsorption capacity.As a result,the optimized sample(NMO-30M)possesses an overpotential of 260 mV at 10 mA cm−2 and excellent long-term durability of 162 h.Importantly,in situ Raman test reveals the rapid formation of high-oxidation-state transition metal hydroxide species,which can further help to improve the catalytic activity of NiMoO_(4) in OER.This work highlights the influence of surface remodification and shed some light on activating catalysts.

Low-Temperature Carbonized Nitrogen-Doped Hard Carbon Nanofiber Toward High-Performance Sodium-Ion Capacitors

Carbon nanofiber(CNF)was widely utilized in the field of electrochemical energy storage due to its superiority of conductivity and mechanics.However,CNF was generally prepared at relatively high temperature.Herein,nitrogen-doped hard carbon nanofibers(NHCNFs)were prepared by a lowtemperature carbonization treatment assisted with electrospinning technology.Density functional theory analysis elucidates the incorporation of nitrogen heteroatoms with various chemical states into carbon matrix would significantly alter the total electronic configurations,leading to the robust adsorption and efficient diffusion of Na atoms on electrode interface.The obtained material carbonized at 600°C(NHCNF-600)presented a reversible specific capacity of 191.0 mAh g^(−1)and no capacity decay after 200 cycles at 1 A g^(−1).It was found that the sodium-intercalated degree had a correlation with the electrochemical impedance.A sodium-intercalated potential of 0.2 V was adopted to lower the electrochemical impedance.The constructed sodium-ion capacitor with activated carbon cathode and presodiated NHCNF-600 anode can present an energy power density of 82.1 Wh kg^(−1)and a power density of 7.0 kW kg^(−1).

Recent advances in preparation of metallic superhydrophobic surface by chemical etching and its applications

In the past few decades,inspired by the superhydrophobic surfaces(SHPS)of animals and plants such as lotus leaves,rose petals,legs of water striders,and wings of butterflies,preparing metal materials with metallic SHPS(MSHPS)have attracted great research interest,due to the great prospect in practical applications.To obtain SHPS on conventional metal materials,it is necessary to construct rough surface,followed by modification with low surface energy substances.In this paper,the action mechanism and the current research status of MSHPS were reviewed through the following aspects.Firstly,the model of wetting theory was presented,and then the progress in MSHPS preparation through chemical etching method was discussed.Secondly,the applications of MSHPS in self-cleaning,anti-icing,corrosion resistance,drag reduction,oil-water separation,and other aspects were introduced.Finally,the challenges encountered in the present application of MSHPS were summarized,and the future research interests were discussed.