The shot-range interaction and the atomic anharmonic vibration are both considered, and then the analytic functions of the Debye temperature, the specific capacity and the thermal conductivity of graphene with the tem...The shot-range interaction and the atomic anharmonic vibration are both considered, and then the analytic functions of the Debye temperature, the specific capacity and the thermal conductivity of graphene with the temperature are obtained. The influence of anharmonic vibration on these thermal physical properties is also investigated. Some theoretical results are given. If only the harmonic approximation is considered, the Debye temperature of the graphene is unrelated to the temperature. If the anharmonic terms are considered, it increases slowly with the increasing temperature. The molar heat capacity of the graphene increases nonlinearly with the increasing temperature. The mean free path of phonons and the thermal conductivity of the graphene decrease nonlinearly with the increasing temperature. The relative changes of the Debye temperature, the specific heat capacity and the thermal conductivity caused by the anharmonic terms increase with the increasing temperature. The anharmonic effect of atomic vibration becomes more significant under higher temperature.展开更多
The use of an aqueous slurry in the manufacture of lithium ion batteries has the advantages of being environmentally friendly,harmless to the human body,and low in production cost.In this study,the factors affecting t...The use of an aqueous slurry in the manufacture of lithium ion batteries has the advantages of being environmentally friendly,harmless to the human body,and low in production cost.In this study,the factors affecting the specific capacity and rate performance of the aqueous Li4Ti5O12 battery were studied,including the Li4Ti5O12 structure,aqueous binder,conductive agent,and surface density.The results show that a spherical secondary particle structure of Li4Ti5O12 is beneficial to its discharge rate performance.In addition,an aqueous binder with high conductivity improves the specific capacity and high rate charge/discharge performance of the battery,and when the amount of binder is 3%,the Li4Ti5O12 battery performs better.A chain structure in the conductive agent also improves the specific capacity and discharge rate performance of the Li4Ti5O12 battery,and increases the degree to which the discharge rate performance of the conductive agent can be further improved.Lastly,the lower the surface density,the better the rate performance of the Li4Ti5O12 battery.展开更多
The specific heat capacities of Cu60Zr20Hfl0Til0 bulk metallic glass （BMG） and crystallized alloys were measured from 2 to 101 K. The effect of crystallization on the specific heat capacity of the BMG was studied. T...The specific heat capacities of Cu60Zr20Hfl0Til0 bulk metallic glass （BMG） and crystallized alloys were measured from 2 to 101 K. The effect of crystallization on the specific heat capacity of the BMG was studied. The effects of crystallization and the relationship between local modes and boson peak in the BMG were discussed. The specific heat capacity deviates from the simple Debye behaviors, showing the presence of local harmonic modes （Einstein oscillator） in the BMG and the crystallized alloy. Model calculation includes the contribution of one Debye mode and two Einstein modes for the BMG, one Debye mode and one Einstein mode for the crystallized alloy, showing an adequate description of the experimental data.展开更多
The thermal decomposition process was studied by the TG–DTA analyzer. The results show that the decomposition process of sodium hydroxyethyl sulfonate consisted of three stages: the mass loss for the first, the secon...The thermal decomposition process was studied by the TG–DTA analyzer. The results show that the decomposition process of sodium hydroxyethyl sulfonate consisted of three stages: the mass loss for the first, the second and third stages may be about the groups of CH_3CH_2OH, CH_3CHO and SO_2 volatilized, respectively. The decomposition residuum of three stages was analyzed by FT-IR, and the results of FT-IR agreed with the decomposition process predicted by theoretical weight loss. The specific heat capacity of sodium hydroxyethyl sulfonate was determined by differential scanning calorimetry(DSC). The melting temperature and melting enthalpy were obtained to be 465.41 K and 25.69 kJ·mol^(-1), respectively. The molar specific heat capacity of sodium hydroxyethyl sulfonate was determinated from 310.15 K to 365.15 K and expressed as a function of temperature.展开更多
Nanofluids are extensively applied in various heat transfer mediums for improving their heat transfer characteristics and hence their performance.Specific heat capacity of nanofluids,as one of the thermophysical prope...Nanofluids are extensively applied in various heat transfer mediums for improving their heat transfer characteristics and hence their performance.Specific heat capacity of nanofluids,as one of the thermophysical properties,performs principal role in heat transfer of thermal mediums utilizing nanofluids.In this regard,different studies have been carried out to investigate the influential factors on nanofluids specific heat.Moreover,several regression models based on correlations or artificial intelligence have been developed for forecasting this property of nanofluids.In the current review paper,influential parameters on the specific heat capacity of nanofluids are introduced.Afterwards,the proposed models for their forecasting and modeling are proposed.According to the reviewed works,concentration and properties of solid structures in addition to temperature affect specific heat capacity to large extent and must be considered as inputs for the models.Moreover,by using other effective factors,the accuracy and comprehensive of the models can be modified.Finally,some suggestions are offered for the upcoming works in the relevant topics.展开更多
A new compound, [（NH2）2C=NH2]＋N（NO2）2-（GDN）, was prepared by mixing ammonium dinitramide （ADN） and guanidine hydrochloride in water. The thermal behavior of GDN was studied under the non-isothermal conditions...A new compound, [（NH2）2C=NH2]＋N（NO2）2-（GDN）, was prepared by mixing ammonium dinitramide （ADN） and guanidine hydrochloride in water. The thermal behavior of GDN was studied under the non-isothermal conditions with DSC and TG/DTG methods. The apparent activation energy（E） and pre-exponential constant（A） of the exothermic decomposition stage of GDN were 118.75 kJ/mol and 10^10.86 s^-1, respectively. The critical temperature of the thermal explosion（Tb） of GDN was 164.09 ℃. The specific heat capacity of GDN was determined with the Micro-DSC method and the theoretical calculation method, and the standard molar specific heat capacity was 234.76 J·mol^-1·K^-1 at 298.15 K. The adiabatic time-to-explosion of GDN was also calculated to be a certain value between 404.80 and 454.95 s.展开更多
The specific heat capacity of NiTi alloy at constant pressure using MDSC (Modulated differential scanning calorimeter) was determined. It was found that the variation tendencies of the specific heat capacity for diffe...The specific heat capacity of NiTi alloy at constant pressure using MDSC (Modulated differential scanning calorimeter) was determined. It was found that the variation tendencies of the specific heat capacity for different phases are different. The fitting equations of the specific heat capacity for martensite and austenite phases were presented. Then, a reason, based on thermodynamic point of view, was proposed to explain the difference of the specific heat capacity between martensitic and austenitic phases. Finally, compared with the specific heat capacity of pure Ni and Ti, it was found that the specific heat capacity of NiTi alloy is inherent to that of pure Ti. When the specific heat capacity of NiTi alloy is calculated by Neuman Kopp, in the temperature region of phase transformation and the temperature higher than 400 K, the results are not desirable.[展开更多
A<sub>2</sub>FeCoO<sub>6-δ</sub> (A = Ca or Sr) is synthesized by the solid-state synthesis method and their specific heat capacities are evaluated at 40˚C using a heat flow meter. The effect ...A<sub>2</sub>FeCoO<sub>6-δ</sub> (A = Ca or Sr) is synthesized by the solid-state synthesis method and their specific heat capacities are evaluated at 40˚C using a heat flow meter. The effect of the A-cation size on the specific heat capacity of these compounds is observed. The specific heat capacity of Sr<sub>2</sub>FeCoO<sub>6-δ</sub> is found to be the highest, and that of Ca<sub>2</sub>FeCoO<sub>6-δ</sub> is the lowest while CaSrFeCoO<sub>6-δ</sub> shows the intermediate value. The specific heat capacity decreases with the decrease of the average A-site ionic radius, demonstrating the relationship between heat capacity and A-site ionic radius. The relationship between specific heat capacity and molar mass is also confirmed as the δ value decreases or molar mass increases from Ca<sub>2</sub>FeCoO<sub>6-δ</sub> to CaSrFeCoO<sub>6-δ</sub> to Sr<sub>2</sub>FeCoO<sub>6-δ</sub>.展开更多
In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,lim...In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,limited active sites and poor electrical conductivity inevitably give rise to the severe performance degradation.To solve these problems,herein,we introduce abundant oxygen vacancies into the flower-likeδ-MnO_(2)nanostructure and effectively modulate the vacancy defects to reach the optimal level(δ-MnO_(2)-x-2.0).The smart design intrinsically tunes the electronic structure,guarantees ion chemisorption-desorption equilibrium and increases the electroactive sites,which not only effectively accelerates charge transfer rate during reaction processes,but also endows more redox reactions,as verified by first-principle calculations.These merits can help the fabricatedδ-MnO_(2)-x-2.0 cathode to present a large specific capacity of 551.8 mAh g^(-1)at 0.5 A g^(-1),high-rate capability of 262.2 mAh g^(-1)at 10 A g^(-1)and an excellent cycle lifespan(83%of capacity retention after 1500 cycles),which is far superior to those of the other metal compound cathodes.In addition,the charge/discharge mechanism of theδ-MnO_(2)-x-2.0 cathode has also been elaborated through ex situ techniques.This work opens up a new pathway for constructing the next-generation high-performance ZIBs cathode materials.展开更多
Currently,the major challenge in terms of research on K-ion batteries is to ensure that they possess satisfactory cycle stability and specific capacity,especially in terms of the intrinsically sluggish kinetics induce...Currently,the major challenge in terms of research on K-ion batteries is to ensure that they possess satisfactory cycle stability and specific capacity,especially in terms of the intrinsically sluggish kinetics induced by the large radius of K+ions.Here,we explore high-performance K-ion half/full batteries with high rate capability,high specific capacity,and extremely durable cycle stability based on carbon nanosheets with tailored N dopants,which can alleviate the change of volume,increase electronic conductivity,and enhance the K+ion adsorption.The as-assembled K-ion half-batteries show an excellent rate capability of 468 mA h g^(-1)at 100 mA g^(-1),which is superior to those of most carbon materials reported to date.Moreover,the as-assembled half-cells have an outstanding life span,running 40,000 cycles over 8 months with a specific capacity retention of 100%at a high current density of 2000 mA g^(-1),and the target full cells deliver a high reversible specific capacity of 146 mA h g^(-1)after 2000 cycles over 2 months,with a specific capacity retention of 113%at a high current density of 500 mA g^(-1),both of which are state of the art in the field of K-ion batteries.This study might provide some insights into and potential avenues for exploration of advanced K-ion batteries with durable stability for practical applications.展开更多
Aqueous zinc-ion batteries(AZIBs)are gaining attention owing to their affordability,high safety,and high energy density,making them a promising solution for large-scale energy storage.However,their performance is hamp...Aqueous zinc-ion batteries(AZIBs)are gaining attention owing to their affordability,high safety,and high energy density,making them a promising solution for large-scale energy storage.However,their performance is hampered by the instability of both the anode-electrolyte interface and the cathode-electrolyte interface.The use of sodium gluconate(SG),an organic sodium salt with multiple hydroxyl groups,as an electrolyte additive is suggested.Experimental and theoretical analyses demonstrate that Na^(+)from SG can intercalate and deintercalate within the associated V_(2)O_(5) cathode during in situ electrochemical processes.This action supports the layered structure of V_(2)O_(5),prevents structural collapse and phase transitions,and enhances Zn^(2+)diffusion kinetics.Additionally,the gluconate anion disrupts the original Zn^(2+)solvation structure,mitigates water-induced side reactions,and suppresses Zn dendrite growth.The synchronous regulation of both the V_(2)O_(5) cathode and Zn anode by the SG additive leads to considerable performance improvements.Zn‖Zn symmetric batteries demonstrate a cycle life exceeding 2800 h at 0.5 mA cm^(-2)and 1 mAh cm^(-2).In Zn‖V_(2)O_(5) full batteries,a high specific capacity of 288.92 mAh g^(-1)and capacity retention of 82.29%are maintained over 1000 cycles at a current density of 2 A g^(-1).This multifunctional additive strategy offers a new pathway for the practical application of AZIBs.展开更多
To improve the slow kinetics and poor mechanical strength of aqueous silver peroxide−aluminum(AgO−Al)battery cathode materials,the effects of different binders including polytetrafluoroethylene(PTFE)and polyvinylpyrro...To improve the slow kinetics and poor mechanical strength of aqueous silver peroxide−aluminum(AgO−Al)battery cathode materials,the effects of different binders including polytetrafluoroethylene(PTFE)and polyvinylpyrrolidone(PVP)on the AgO cathode material were investigated.The samples were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),cyclic voltammetry(CV),electrochemical impedance spectrum(EIS),and galvanostatic discharge.In contrast to the pure AgO and AgO−PTFE electrodes,the results demonstrated that the PVP effectively bound the electrode materials together.The prepared AgO−PVP as the cathode material of AgO−Al batteries could improve the battery capacity,exhibiting a high specific capacity(389.95 mA·h/g at 500 mA/cm^(2)),a high operating voltage(1.75 V at 500 mA/cm^(2)),a maximum energy density(665.65 W·h/kg),and a maximum power density(5236 W/kg).Furthermore,the electrochemical mechanism of the AgO−PVP cathode material was examined,revealing that the electrode exhibited rapid ion diffusion and effective interfacial ion/electron transport.展开更多
Lithium-rich manganese-based oxides(LRMOs;xLi_(2)MnO_(3)(1−x)LiMO_(2);M=transition metal,0<x<1)with excellent specific capacity(>300 mAh/g)and high operating voltage(≥4.8V)are the preferred cathode materials...Lithium-rich manganese-based oxides(LRMOs;xLi_(2)MnO_(3)(1−x)LiMO_(2);M=transition metal,0<x<1)with excellent specific capacity(>300 mAh/g)and high operating voltage(≥4.8V)are the preferred cathode materials for high-specific-energy lithium metal batteries(LMBs)[1].However,LRMOs face a series of serious problems such as irreversible lattice oxygen loss,transition metal(TM)migration,phase transfer,and interfacial side reactions at high voltages,resulting in rapid decay of capacity and voltage[2,3].In situ generating well-functional CEI through electrolyte engineering can effectively address these challenges[4].展开更多
Customized design of well-defined cathode structures with abundant adsorption sites and rapid diffusion dynamics,holds great promise in filling capacity gap of carbonaceous cathodes towards high-performance Zn-ion hyb...Customized design of well-defined cathode structures with abundant adsorption sites and rapid diffusion dynamics,holds great promise in filling capacity gap of carbonaceous cathodes towards high-performance Zn-ion hybrid supercapacitors(ZHC).Herein,we fabricate a series of dynamics-oriented hierarchical porous carbons derived from the unique organic-inorganic interpenetrating polymer networks.The interpenetrating polymer networks are obtained through physically knitting polyferric chloride(PFC)network into the highly crosslinked resorcinol-formaldehyde(RF)network.Instead of covalent bonding,physical interpenetrating force in such RF-PFC networks efficiently relieves the RF skeleton shrinkage upon pyrolysis.Meanwhile,the in-situ PFC network sacrifices as a structure-directing agent to suppress the macrophase separation,and correspondingly 3D hierarchical porous structure with plentiful ion-diffusion channels(pore volume of 1.35 cm^(3)/g)is generated in the representative HPC_(4) via nanospace occupation and swelling effect.Further removal of Fe fillers leaves behind a large accessible specific surface area of 1550 m^(2)/g for enhanced Zn-ion adsorption.When used as the cathode for ZHC,HPC_(4) demonstrates a remarkable electrochemical performance with a specific capacity of 215.1 mAh/g at 0.5 A/g and a high Zn^(2+)ion diffusion coefficient of 11.1×10^(-18)cm^(2)/s.The ZHC device yields 117.0 Wh/kg energy output at a power density of 272.1 W/kg,coupled with good cycle lifespan(100,000 cycles@10 A/g).This work inspires innovative insights to accelerate Zn diffusion dynamics by structure elaboration towards high-capacity cathode materials.展开更多
Iron disulfide(FeS_(2))has been widely used in thermal batteries because of its high theoretical specific capacity and voltage plateau.However,low thermal decomposition temperature,poor conductivity and inferior actua...Iron disulfide(FeS_(2))has been widely used in thermal batteries because of its high theoretical specific capacity and voltage plateau.However,low thermal decomposition temperature,poor conductivity and inferior actual specific capacity limit its wide applications.Herein,we report a gold-doped FeS_(2)(FeS_(2)-Au),which not only reduces the band gap of the FeS_(2)crystals but also enriches the electron transport path of FeS_(2)by the formation of Au nanoparticles.First-principles calculation shows that the diffusion energy barrier of lithium-ion is reduced after the Au-doped FeS_(2).In addition,Au increases the electron cloud density around sulfur atoms,which helps to enhance the stability of Fe-S covalent bonds and thus results in better thermal stability of FeS_(2).When the Au content is 130μg·g^(-1)(FeS_(2)-Au_(4)),the thermal decomposition temperature(TG5%)of FeS_(2)-Au is 72.2℃ higher than that of pristine FeS_(2).At a discharge temperature of 500℃,a current density of 200 mA·cm^(-2) and a cutoff voltage of 1.4 V,FeS_(2)-Au_(4)demonstrates superior specific capacity and high specific energy compared to FeS_(2).More precisely,the specific capacity of FeS_(2)-Au_(4)attains a value of 379 mAh·g^(-1),with a corresponding specific energy of 714 Wh·kg^(-1).In contrast,the discharge specific capacity and specific energy of FeS_(2)are lower,amounting to 348 mAh·g^(-1)and 656 Wh·kg^(-1),respectively.This study offers a novel approach to enhancing the electrochemical performance of FeS_(2)in high-temperature molten salt electrochemical systems(thermal batteries),thereby laying a solid foundation for its potential practical application.展开更多
LithiumvanadatesLiV_(3)O_(8)-LiV_(6)O_(15)(LVO)witha heterojunction structure are synthesized using a conventional high-temperature solid-state method to address the challenges of low ionic conductivity,rapid capacity...LithiumvanadatesLiV_(3)O_(8)-LiV_(6)O_(15)(LVO)witha heterojunction structure are synthesized using a conventional high-temperature solid-state method to address the challenges of low ionic conductivity,rapid capacity decay,and poor cycling performance in conventional lithium-ion battery cathode materials.The charge-discharge processes of LVO span multiple platforms,delivering an impressive specific discharge capacity of 219.4 mAh.g^(-1) at 1C.Remarkably,LVO exhibits a high-capacity retention rate of 81.3%after 800 cycles within the typical operating voltage range of lithium-ion batteries(2.8-4.3V).Rate capability tests and electrochemical impedance spectroscopy(EIS)reveal that,compared to traditional cathode materials,LVO significantly enhances Li*diffusion rates(D_(Li*))and reduces charge transfer resistance(Ret).展开更多
In the field of nano energy,investigating the specific heat capacity and coordination number of nano-confined water is highly significant for gaining a better understanding of the energy and microstructure of confined...In the field of nano energy,investigating the specific heat capacity and coordination number of nano-confined water is highly significant for gaining a better understanding of the energy and microstructure of confined water.In this work,we employed the method of molecular dynamics(MD)simulation to calculate the specific heat capacity at constant volume and coordination number of water molecules confined in carbon nanotubes(CNTs)under different conditions(T=600-700 K,P=21.776 and 25 MPa,CNT diameter=0.949-5.017nm).The results showed that near the critical point,the specific heat capacity at constant volume of confined water was lower than that of bulk water,and the energy fluctuation showed a trend of first increasing and then remaining unchanged with the increase of temperature and CNT diameter.Among them,the saturation point of temperature is 650 K(reduced pressure P_(r)=1)and 660 K(P_(r)=1.15),and the saturation point of CNT diameter is 2.034 nm.Additionally,the pseudo-critical temperature of confined water was the same as bulk water,and it increased with the increase of critical pressure.Moreover,with the increase of CNT diameter,the coordination number of confined water increased rapidly,and reaches the saturation state when the CNT diameter is 2.034 nm.This investigation revealed the mass and energy characteristics of nano-confined water near the critical point,which could provide guidance for the critical phase transition of nano-confined water.展开更多
The water characteristic curve for aeolian sand in two processes of wetting and drying was obtained by the negative water column technique.The values of fitting parameters were calculated according to Van Genuchten fo...The water characteristic curve for aeolian sand in two processes of wetting and drying was obtained by the negative water column technique.The values of fitting parameters were calculated according to Van Genuchten formula and the parameters that characterized the prosperities of aeolian sand such as the unsaturated infiltration coefficient and specific water capacity were obtained.The results showed that the water characteristic curve for aeolian sand in wetting process had greater hysteresis quality than ...展开更多
The aqueous rechargeable Zn-ion batteries based on the safe,low cost and environmental benignity aqueous electrolytes are one of the most compelling candidates for large scale energy storage applications.However,pursu...The aqueous rechargeable Zn-ion batteries based on the safe,low cost and environmental benignity aqueous electrolytes are one of the most compelling candidates for large scale energy storage applications.However,pursuing suitable insertion materials may be a great challenge due to the strong electrostatic interaction between Zn^(^(2+))and cathode materials.Hence,a novel NaV_(6)O_(15)/V_(2)O_(5) skin-core heterostructure nanowire is reported via a one-step hydrothermal method and subsequent calcination for high-stable aqueous Zn-ion batteries(ZIBs).The NaV_(6)O_(15)/V_(2)O_(5) cathode delivers high specific capacity of 390 m Ah/g at 0.3 A/g and outstanding cycling stability of 267 m Ah/g at 5 A/g with high capacity retention over 92.3%after 3000 cycles.The superior electrochemical performances are attributed to the synergistic effect of skin-core heterostructured NaV_(6)O_(15)/V_(2)O_(5),in which the sheath of NaV_(6)O_(15) possesses high stability and conductivity,and the V_(2)O_(5) endows high specific capacity.Besides,the heterojunction structure not only accelerates intercalation kinetics of Zn^(2+)transport but also further consolidates the stability of the layers of V_(2)O_(5) during the cyclic process.This work provides a new perspective in developing feasible insertion materials for rechargeable aqueous ZIBs.展开更多
Nickel selenide(NiSe)has been a promising positive electrode for hybrid supercapacitors due to its multiple oxidation states,tunability,and high specific capacity.However,sluggish ion transfers and particle agglomerat...Nickel selenide(NiSe)has been a promising positive electrode for hybrid supercapacitors due to its multiple oxidation states,tunability,and high specific capacity.However,sluggish ion transfers and particle agglomeration hamper its electrochemical performance.In the present study,we have grown NiSe nanoparticles on two-dimensional(2D)graphitic carbon nitride(g-C_(3)N_(4))nanosheets to realize three-dimensional(3D)architecture.The 2D support,high nitrogen content,and features of g-C_(3)N_(4)enhanced the specific capacity of the NiSe/g-C_(3)N_(4)nanocomposite material.The resulting nanocomposite shows a specific capacity of 320 mA h g^(-1)at a current density of 1 A g^(-1),which is considerably higher than pristine NiSe.Later,the hybrid supercapacitor(HSC)device was fabricated using NiSe/g-C_(3)N_(4)composite as positive and activated carbon(AC)as negative electrodes.The cell delivered an energy density of 52.5 Wh kg^(-1)at a power density of 1488 W kg^(-1)with excellent cyclic stability of 84.9%over 8000 cycles.The electrochemical performance enhancement corresponds to a 3D structure,high electrochemical active sites,and improved charge transportation at the electrode/electrolyte interface.Thus,the present work offers an easy approach and architectural design for high-performance HSC.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11574253the Scientific and Technological Research Program of Chongqing Municipal Education Commission under Grant Nos KJ1601111 and KJ1601118the Basic and Frontier Research Projects of Chongqing under Grant No cstc2015jcyjA40054
文摘The shot-range interaction and the atomic anharmonic vibration are both considered, and then the analytic functions of the Debye temperature, the specific capacity and the thermal conductivity of graphene with the temperature are obtained. The influence of anharmonic vibration on these thermal physical properties is also investigated. Some theoretical results are given. If only the harmonic approximation is considered, the Debye temperature of the graphene is unrelated to the temperature. If the anharmonic terms are considered, it increases slowly with the increasing temperature. The molar heat capacity of the graphene increases nonlinearly with the increasing temperature. The mean free path of phonons and the thermal conductivity of the graphene decrease nonlinearly with the increasing temperature. The relative changes of the Debye temperature, the specific heat capacity and the thermal conductivity caused by the anharmonic terms increase with the increasing temperature. The anharmonic effect of atomic vibration becomes more significant under higher temperature.
文摘The use of an aqueous slurry in the manufacture of lithium ion batteries has the advantages of being environmentally friendly,harmless to the human body,and low in production cost.In this study,the factors affecting the specific capacity and rate performance of the aqueous Li4Ti5O12 battery were studied,including the Li4Ti5O12 structure,aqueous binder,conductive agent,and surface density.The results show that a spherical secondary particle structure of Li4Ti5O12 is beneficial to its discharge rate performance.In addition,an aqueous binder with high conductivity improves the specific capacity and high rate charge/discharge performance of the battery,and when the amount of binder is 3%,the Li4Ti5O12 battery performs better.A chain structure in the conductive agent also improves the specific capacity and discharge rate performance of the Li4Ti5O12 battery,and increases the degree to which the discharge rate performance of the conductive agent can be further improved.Lastly,the lower the surface density,the better the rate performance of the Li4Ti5O12 battery.
基金Project(082102230035)supported by the Foundation of Science and Technology Department of Henan Province,China
文摘The specific heat capacities of Cu60Zr20Hfl0Til0 bulk metallic glass （BMG） and crystallized alloys were measured from 2 to 101 K. The effect of crystallization on the specific heat capacity of the BMG was studied. The effects of crystallization and the relationship between local modes and boson peak in the BMG were discussed. The specific heat capacity deviates from the simple Debye behaviors, showing the presence of local harmonic modes （Einstein oscillator） in the BMG and the crystallized alloy. Model calculation includes the contribution of one Debye mode and two Einstein modes for the BMG, one Debye mode and one Einstein mode for the crystallized alloy, showing an adequate description of the experimental data.
文摘The thermal decomposition process was studied by the TG–DTA analyzer. The results show that the decomposition process of sodium hydroxyethyl sulfonate consisted of three stages: the mass loss for the first, the second and third stages may be about the groups of CH_3CH_2OH, CH_3CHO and SO_2 volatilized, respectively. The decomposition residuum of three stages was analyzed by FT-IR, and the results of FT-IR agreed with the decomposition process predicted by theoretical weight loss. The specific heat capacity of sodium hydroxyethyl sulfonate was determined by differential scanning calorimetry(DSC). The melting temperature and melting enthalpy were obtained to be 465.41 K and 25.69 kJ·mol^(-1), respectively. The molar specific heat capacity of sodium hydroxyethyl sulfonate was determinated from 310.15 K to 365.15 K and expressed as a function of temperature.
基金This work was supported by College of Engineering and Technology,the American University of the Middle East,Kuwait.Homepage:https://www.aum.edu.kw.
文摘Nanofluids are extensively applied in various heat transfer mediums for improving their heat transfer characteristics and hence their performance.Specific heat capacity of nanofluids,as one of the thermophysical properties,performs principal role in heat transfer of thermal mediums utilizing nanofluids.In this regard,different studies have been carried out to investigate the influential factors on nanofluids specific heat.Moreover,several regression models based on correlations or artificial intelligence have been developed for forecasting this property of nanofluids.In the current review paper,influential parameters on the specific heat capacity of nanofluids are introduced.Afterwards,the proposed models for their forecasting and modeling are proposed.According to the reviewed works,concentration and properties of solid structures in addition to temperature affect specific heat capacity to large extent and must be considered as inputs for the models.Moreover,by using other effective factors,the accuracy and comprehensive of the models can be modified.Finally,some suggestions are offered for the upcoming works in the relevant topics.
基金Supported by the National Natural Science Foundation of China(No.20803058)Xi’an Scientific and Technical Plan Foundation, China(No.YF07106).
文摘A new compound, [（NH2）2C=NH2]＋N（NO2）2-（GDN）, was prepared by mixing ammonium dinitramide （ADN） and guanidine hydrochloride in water. The thermal behavior of GDN was studied under the non-isothermal conditions with DSC and TG/DTG methods. The apparent activation energy（E） and pre-exponential constant（A） of the exothermic decomposition stage of GDN were 118.75 kJ/mol and 10^10.86 s^-1, respectively. The critical temperature of the thermal explosion（Tb） of GDN was 164.09 ℃. The specific heat capacity of GDN was determined with the Micro-DSC method and the theoretical calculation method, and the standard molar specific heat capacity was 234.76 J·mol^-1·K^-1 at 298.15 K. The adiabatic time-to-explosion of GDN was also calculated to be a certain value between 404.80 and 454.95 s.
文摘The specific heat capacity of NiTi alloy at constant pressure using MDSC (Modulated differential scanning calorimeter) was determined. It was found that the variation tendencies of the specific heat capacity for different phases are different. The fitting equations of the specific heat capacity for martensite and austenite phases were presented. Then, a reason, based on thermodynamic point of view, was proposed to explain the difference of the specific heat capacity between martensitic and austenitic phases. Finally, compared with the specific heat capacity of pure Ni and Ti, it was found that the specific heat capacity of NiTi alloy is inherent to that of pure Ti. When the specific heat capacity of NiTi alloy is calculated by Neuman Kopp, in the temperature region of phase transformation and the temperature higher than 400 K, the results are not desirable.[
文摘A<sub>2</sub>FeCoO<sub>6-δ</sub> (A = Ca or Sr) is synthesized by the solid-state synthesis method and their specific heat capacities are evaluated at 40˚C using a heat flow meter. The effect of the A-cation size on the specific heat capacity of these compounds is observed. The specific heat capacity of Sr<sub>2</sub>FeCoO<sub>6-δ</sub> is found to be the highest, and that of Ca<sub>2</sub>FeCoO<sub>6-δ</sub> is the lowest while CaSrFeCoO<sub>6-δ</sub> shows the intermediate value. The specific heat capacity decreases with the decrease of the average A-site ionic radius, demonstrating the relationship between heat capacity and A-site ionic radius. The relationship between specific heat capacity and molar mass is also confirmed as the δ value decreases or molar mass increases from Ca<sub>2</sub>FeCoO<sub>6-δ</sub> to CaSrFeCoO<sub>6-δ</sub> to Sr<sub>2</sub>FeCoO<sub>6-δ</sub>.
基金supported by the National Natural Science Foundation of China under Grant Nos.52072196,52002200,52102106 and 52002199Major Basic Research Program of the Natural Science Foundation of Shandong Province under Grant No.ZR2020ZD09+2 种基金the Natural Science Foundation of Shandong Province under Grant No.ZR2020QE063the Innovation and Technology Program of Shandong Province under Grant No.2020KJA004the Taishan Scholars Program of Shandong Province under Grant No.ts201511034
文摘In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,limited active sites and poor electrical conductivity inevitably give rise to the severe performance degradation.To solve these problems,herein,we introduce abundant oxygen vacancies into the flower-likeδ-MnO_(2)nanostructure and effectively modulate the vacancy defects to reach the optimal level(δ-MnO_(2)-x-2.0).The smart design intrinsically tunes the electronic structure,guarantees ion chemisorption-desorption equilibrium and increases the electroactive sites,which not only effectively accelerates charge transfer rate during reaction processes,but also endows more redox reactions,as verified by first-principle calculations.These merits can help the fabricatedδ-MnO_(2)-x-2.0 cathode to present a large specific capacity of 551.8 mAh g^(-1)at 0.5 A g^(-1),high-rate capability of 262.2 mAh g^(-1)at 10 A g^(-1)and an excellent cycle lifespan(83%of capacity retention after 1500 cycles),which is far superior to those of the other metal compound cathodes.In addition,the charge/discharge mechanism of theδ-MnO_(2)-x-2.0 cathode has also been elaborated through ex situ techniques.This work opens up a new pathway for constructing the next-generation high-performance ZIBs cathode materials.
基金National Natural Science Foundation of China,Grant/Award Numbers:51972178,52202061Hunan Provincial Nature Science Foundation,Grant/Award Number:2022JJ40068。
文摘Currently,the major challenge in terms of research on K-ion batteries is to ensure that they possess satisfactory cycle stability and specific capacity,especially in terms of the intrinsically sluggish kinetics induced by the large radius of K+ions.Here,we explore high-performance K-ion half/full batteries with high rate capability,high specific capacity,and extremely durable cycle stability based on carbon nanosheets with tailored N dopants,which can alleviate the change of volume,increase electronic conductivity,and enhance the K+ion adsorption.The as-assembled K-ion half-batteries show an excellent rate capability of 468 mA h g^(-1)at 100 mA g^(-1),which is superior to those of most carbon materials reported to date.Moreover,the as-assembled half-cells have an outstanding life span,running 40,000 cycles over 8 months with a specific capacity retention of 100%at a high current density of 2000 mA g^(-1),and the target full cells deliver a high reversible specific capacity of 146 mA h g^(-1)after 2000 cycles over 2 months,with a specific capacity retention of 113%at a high current density of 500 mA g^(-1),both of which are state of the art in the field of K-ion batteries.This study might provide some insights into and potential avenues for exploration of advanced K-ion batteries with durable stability for practical applications.
基金supported by the Battery Energy Storage Testing Center of Chongqing through their provision of testing support and technical assistance。
文摘Aqueous zinc-ion batteries(AZIBs)are gaining attention owing to their affordability,high safety,and high energy density,making them a promising solution for large-scale energy storage.However,their performance is hampered by the instability of both the anode-electrolyte interface and the cathode-electrolyte interface.The use of sodium gluconate(SG),an organic sodium salt with multiple hydroxyl groups,as an electrolyte additive is suggested.Experimental and theoretical analyses demonstrate that Na^(+)from SG can intercalate and deintercalate within the associated V_(2)O_(5) cathode during in situ electrochemical processes.This action supports the layered structure of V_(2)O_(5),prevents structural collapse and phase transitions,and enhances Zn^(2+)diffusion kinetics.Additionally,the gluconate anion disrupts the original Zn^(2+)solvation structure,mitigates water-induced side reactions,and suppresses Zn dendrite growth.The synchronous regulation of both the V_(2)O_(5) cathode and Zn anode by the SG additive leads to considerable performance improvements.Zn‖Zn symmetric batteries demonstrate a cycle life exceeding 2800 h at 0.5 mA cm^(-2)and 1 mAh cm^(-2).In Zn‖V_(2)O_(5) full batteries,a high specific capacity of 288.92 mAh g^(-1)and capacity retention of 82.29%are maintained over 1000 cycles at a current density of 2 A g^(-1).This multifunctional additive strategy offers a new pathway for the practical application of AZIBs.
基金supported by the Fundamental Research Funds for the Central Universities of Central South University,China(No.2022XQLH046)the Technical Area Fund of Foundation Strengthening,China(No.2022-JCJQ-ZD-174-00-20)National Defense Basic Scientific Research Projects,China,and Central South University−Zijin Mining Technical Cooperation Development Project,China.
文摘To improve the slow kinetics and poor mechanical strength of aqueous silver peroxide−aluminum(AgO−Al)battery cathode materials,the effects of different binders including polytetrafluoroethylene(PTFE)and polyvinylpyrrolidone(PVP)on the AgO cathode material were investigated.The samples were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),cyclic voltammetry(CV),electrochemical impedance spectrum(EIS),and galvanostatic discharge.In contrast to the pure AgO and AgO−PTFE electrodes,the results demonstrated that the PVP effectively bound the electrode materials together.The prepared AgO−PVP as the cathode material of AgO−Al batteries could improve the battery capacity,exhibiting a high specific capacity(389.95 mA·h/g at 500 mA/cm^(2)),a high operating voltage(1.75 V at 500 mA/cm^(2)),a maximum energy density(665.65 W·h/kg),and a maximum power density(5236 W/kg).Furthermore,the electrochemical mechanism of the AgO−PVP cathode material was examined,revealing that the electrode exhibited rapid ion diffusion and effective interfacial ion/electron transport.
文摘Lithium-rich manganese-based oxides(LRMOs;xLi_(2)MnO_(3)(1−x)LiMO_(2);M=transition metal,0<x<1)with excellent specific capacity(>300 mAh/g)and high operating voltage(≥4.8V)are the preferred cathode materials for high-specific-energy lithium metal batteries(LMBs)[1].However,LRMOs face a series of serious problems such as irreversible lattice oxygen loss,transition metal(TM)migration,phase transfer,and interfacial side reactions at high voltages,resulting in rapid decay of capacity and voltage[2,3].In situ generating well-functional CEI through electrolyte engineering can effectively address these challenges[4].
基金financially supported by the National Natural Science Foundation of China(Nos.22272118,22172111,21905207,and 22309134)the Science and Technology Commission of Shanghai Municipality(Nos.22ZR1464100,20ZR1460300,and 19DZ2271500)+3 种基金China Postdoctoral Science Foundation(No.2022M712402)Shanghai Rising-Star Program(No.23YF1449200)Zhejiang Provincial Science and Technology Project(No.2022C01182)the Fundamental Research Funds for the Central Universities(Nos.22120210529 and 2023-3-YB-07)。
文摘Customized design of well-defined cathode structures with abundant adsorption sites and rapid diffusion dynamics,holds great promise in filling capacity gap of carbonaceous cathodes towards high-performance Zn-ion hybrid supercapacitors(ZHC).Herein,we fabricate a series of dynamics-oriented hierarchical porous carbons derived from the unique organic-inorganic interpenetrating polymer networks.The interpenetrating polymer networks are obtained through physically knitting polyferric chloride(PFC)network into the highly crosslinked resorcinol-formaldehyde(RF)network.Instead of covalent bonding,physical interpenetrating force in such RF-PFC networks efficiently relieves the RF skeleton shrinkage upon pyrolysis.Meanwhile,the in-situ PFC network sacrifices as a structure-directing agent to suppress the macrophase separation,and correspondingly 3D hierarchical porous structure with plentiful ion-diffusion channels(pore volume of 1.35 cm^(3)/g)is generated in the representative HPC_(4) via nanospace occupation and swelling effect.Further removal of Fe fillers leaves behind a large accessible specific surface area of 1550 m^(2)/g for enhanced Zn-ion adsorption.When used as the cathode for ZHC,HPC_(4) demonstrates a remarkable electrochemical performance with a specific capacity of 215.1 mAh/g at 0.5 A/g and a high Zn^(2+)ion diffusion coefficient of 11.1×10^(-18)cm^(2)/s.The ZHC device yields 117.0 Wh/kg energy output at a power density of 272.1 W/kg,coupled with good cycle lifespan(100,000 cycles@10 A/g).This work inspires innovative insights to accelerate Zn diffusion dynamics by structure elaboration towards high-capacity cathode materials.
基金supported by the Central South University Innovation-Driven Research Programme(No.2023CXQD009).
文摘Iron disulfide(FeS_(2))has been widely used in thermal batteries because of its high theoretical specific capacity and voltage plateau.However,low thermal decomposition temperature,poor conductivity and inferior actual specific capacity limit its wide applications.Herein,we report a gold-doped FeS_(2)(FeS_(2)-Au),which not only reduces the band gap of the FeS_(2)crystals but also enriches the electron transport path of FeS_(2)by the formation of Au nanoparticles.First-principles calculation shows that the diffusion energy barrier of lithium-ion is reduced after the Au-doped FeS_(2).In addition,Au increases the electron cloud density around sulfur atoms,which helps to enhance the stability of Fe-S covalent bonds and thus results in better thermal stability of FeS_(2).When the Au content is 130μg·g^(-1)(FeS_(2)-Au_(4)),the thermal decomposition temperature(TG5%)of FeS_(2)-Au is 72.2℃ higher than that of pristine FeS_(2).At a discharge temperature of 500℃,a current density of 200 mA·cm^(-2) and a cutoff voltage of 1.4 V,FeS_(2)-Au_(4)demonstrates superior specific capacity and high specific energy compared to FeS_(2).More precisely,the specific capacity of FeS_(2)-Au_(4)attains a value of 379 mAh·g^(-1),with a corresponding specific energy of 714 Wh·kg^(-1).In contrast,the discharge specific capacity and specific energy of FeS_(2)are lower,amounting to 348 mAh·g^(-1)and 656 Wh·kg^(-1),respectively.This study offers a novel approach to enhancing the electrochemical performance of FeS_(2)in high-temperature molten salt electrochemical systems(thermal batteries),thereby laying a solid foundation for its potential practical application.
基金supported by the National Natural Science Foundation of China(Nos.52125405 and U22A20108)Thailand Science Research and Innovation Fund Chulalongkorn University,National Research Council of Thailand(NRCT)+1 种基金Chulalongkorn University(No.42A660383)the Hub of Talents:Sustainable Materials for Circular Economy,National Research Council of Thailand(NRCT).
文摘LithiumvanadatesLiV_(3)O_(8)-LiV_(6)O_(15)(LVO)witha heterojunction structure are synthesized using a conventional high-temperature solid-state method to address the challenges of low ionic conductivity,rapid capacity decay,and poor cycling performance in conventional lithium-ion battery cathode materials.The charge-discharge processes of LVO span multiple platforms,delivering an impressive specific discharge capacity of 219.4 mAh.g^(-1) at 1C.Remarkably,LVO exhibits a high-capacity retention rate of 81.3%after 800 cycles within the typical operating voltage range of lithium-ion batteries(2.8-4.3V).Rate capability tests and electrochemical impedance spectroscopy(EIS)reveal that,compared to traditional cathode materials,LVO significantly enhances Li*diffusion rates(D_(Li*))and reduces charge transfer resistance(Ret).
基金financially supported by the National Key R&D Program of China(2020YFA0714400)the Fundamental Research Funds for the Central Universities(xzy022023036)。
文摘In the field of nano energy,investigating the specific heat capacity and coordination number of nano-confined water is highly significant for gaining a better understanding of the energy and microstructure of confined water.In this work,we employed the method of molecular dynamics(MD)simulation to calculate the specific heat capacity at constant volume and coordination number of water molecules confined in carbon nanotubes(CNTs)under different conditions(T=600-700 K,P=21.776 and 25 MPa,CNT diameter=0.949-5.017nm).The results showed that near the critical point,the specific heat capacity at constant volume of confined water was lower than that of bulk water,and the energy fluctuation showed a trend of first increasing and then remaining unchanged with the increase of temperature and CNT diameter.Among them,the saturation point of temperature is 650 K(reduced pressure P_(r)=1)and 660 K(P_(r)=1.15),and the saturation point of CNT diameter is 2.034 nm.Additionally,the pseudo-critical temperature of confined water was the same as bulk water,and it increased with the increase of critical pressure.Moreover,with the increase of CNT diameter,the coordination number of confined water increased rapidly,and reaches the saturation state when the CNT diameter is 2.034 nm.This investigation revealed the mass and energy characteristics of nano-confined water near the critical point,which could provide guidance for the critical phase transition of nano-confined water.
基金Supported by Key Project of Science and Technology Research of Ministry of Education(308021)Chang Jiang Scholars Innovation Team of Ministry of Education(IRT0811)Geological Survey Project of China Geological Survey(1212010331302)~~
文摘The water characteristic curve for aeolian sand in two processes of wetting and drying was obtained by the negative water column technique.The values of fitting parameters were calculated according to Van Genuchten formula and the parameters that characterized the prosperities of aeolian sand such as the unsaturated infiltration coefficient and specific water capacity were obtained.The results showed that the water characteristic curve for aeolian sand in wetting process had greater hysteresis quality than ...
基金the financial support from the National Natural Science Foundation of China(Nos.21878231 and 51603145)the Tianjin Natural Science Foundation of China(Nos.17JC ZDJ38100 and 19JCZDJC37300)+2 种基金the Science and Technology Plans of Tianjin(Nos.17PT SYJC00040 and 18PTSY JC00180)the China National Textile and Apparel Council(J201406)the China Petroleum Chemical Co Technology Development Project(216090 and 218008-6)。
文摘The aqueous rechargeable Zn-ion batteries based on the safe,low cost and environmental benignity aqueous electrolytes are one of the most compelling candidates for large scale energy storage applications.However,pursuing suitable insertion materials may be a great challenge due to the strong electrostatic interaction between Zn^(^(2+))and cathode materials.Hence,a novel NaV_(6)O_(15)/V_(2)O_(5) skin-core heterostructure nanowire is reported via a one-step hydrothermal method and subsequent calcination for high-stable aqueous Zn-ion batteries(ZIBs).The NaV_(6)O_(15)/V_(2)O_(5) cathode delivers high specific capacity of 390 m Ah/g at 0.3 A/g and outstanding cycling stability of 267 m Ah/g at 5 A/g with high capacity retention over 92.3%after 3000 cycles.The superior electrochemical performances are attributed to the synergistic effect of skin-core heterostructured NaV_(6)O_(15)/V_(2)O_(5),in which the sheath of NaV_(6)O_(15) possesses high stability and conductivity,and the V_(2)O_(5) endows high specific capacity.Besides,the heterojunction structure not only accelerates intercalation kinetics of Zn^(2+)transport but also further consolidates the stability of the layers of V_(2)O_(5) during the cyclic process.This work provides a new perspective in developing feasible insertion materials for rechargeable aqueous ZIBs.
基金the financial support from UGC NET-JRF(517906)support from UGC NFOBC(202021-201610071195)+1 种基金funding from SERB(EEQ/2022/001076)DST-SERB for startup research grant(SRG/2021/001791)。
文摘Nickel selenide(NiSe)has been a promising positive electrode for hybrid supercapacitors due to its multiple oxidation states,tunability,and high specific capacity.However,sluggish ion transfers and particle agglomeration hamper its electrochemical performance.In the present study,we have grown NiSe nanoparticles on two-dimensional(2D)graphitic carbon nitride(g-C_(3)N_(4))nanosheets to realize three-dimensional(3D)architecture.The 2D support,high nitrogen content,and features of g-C_(3)N_(4)enhanced the specific capacity of the NiSe/g-C_(3)N_(4)nanocomposite material.The resulting nanocomposite shows a specific capacity of 320 mA h g^(-1)at a current density of 1 A g^(-1),which is considerably higher than pristine NiSe.Later,the hybrid supercapacitor(HSC)device was fabricated using NiSe/g-C_(3)N_(4)composite as positive and activated carbon(AC)as negative electrodes.The cell delivered an energy density of 52.5 Wh kg^(-1)at a power density of 1488 W kg^(-1)with excellent cyclic stability of 84.9%over 8000 cycles.The electrochemical performance enhancement corresponds to a 3D structure,high electrochemical active sites,and improved charge transportation at the electrode/electrolyte interface.Thus,the present work offers an easy approach and architectural design for high-performance HSC.
