Recent Advances in Fibrous Materials for Hydroelectricity Generation

Depleting fossil energy sources and conventional polluting power generation pose a threat to sustainable development.Hydroelectricity generation from ubiquitous and spontaneous phase transitions between liquid and gaseous water has been considered a promising strategy for mitigating the energy crisis.Fibrous materials with unique flexibility,processability,multifunctionality,and practicability have been widely applied for fibrous materials-based hydroelectricity generation(FHG).In this review,the power generation mechanisms,design principles,and electricity enhancement factors of FHG are first introduced.Then,the fabrication strategies and characteristics of varied constructions including 1D fiber,1D yarn,2D fabric,2D membrane,3D fibrous framework,and 3D fibrous gel are demonstrated.Afterward,the advanced functions of FHG during water harvesting,proton dissociation,ion separation,and charge accumulation processes are analyzed in detail.Moreover,the potential applications including power supply,energy storage,electrical sensor,and information expression are also discussed.Finally,some existing challenges are considered and prospects for future development are sincerely proposed.

Interpenetrated Structures for Enhancing Ion Diffusion Kinetics in Electrochemical Energy Storage Devices

The architectural design of electrodes offers new opportunities for next-generation electrochemical energy storage devices(EESDs)by increasing surface area,thickness,and active materials mass loading while maintaining good ion diffusion through optimized electrode tortuosity.However,conventional thick electrodes increase ion diffusion length and cause larger ion concentration gradients,limiting reaction kinetics.We demonstrate a strategy for building interpenetrated structures that shortens ion diffusion length and reduces ion concentration inhomogeneity.This free-standing device structure also avoids short-circuiting without needing a separator.The feature size and number of interpenetrated units can be adjusted during printing to balance surface area and ion diffusion.Starting with a 3D-printed interpenetrated polymer substrate,we metallize it to make it conductive.This substrate has two individually addressable electrodes,allowing selective electrodeposition of energy storage materials.Using a Zn//MnO_(2) battery as a model system,the interpenetrated device outperforms conventional separate electrode configurations,improving volumetric energy density by 221%and exhibiting a higher capacity retention rate of 49%compared to 35%at temperatures from 20 to 0℃.Our study introduces a new EESD architecture applicable to Li-ion,Na-ion batteries,supercapacitors,etc.

Accelerating lithium ion transport via increasing the entropy of the electrolyte for stable lithium metal batteries

Promoting inorganic-rich solid-electrolyte interphase (SEI) formation by constructing anion-rich solvated structures is a promising strategy for improving the long-term cycling of lithium-metal batteries.However,the increase of anions within the solvated structure inevitably reduces the coordination of Li^(+) with the solvent,which leads to a low lithium diffusion coefficient and a decreased lithium conductivity.Here,high entropy electrolyte is achieved by increasing the molecular diversity in electrolyte.Multiple anions (TFSI^(-),FSI^(-),NO_(3)^(-) and PF_(6)^(-)) presented in entropy electrolyte individually coordinate with Li^(+),creating a diverse and anion-rich solvation structure.The large variety of solvation structures leads to a diversified Li^(+) diffusion barriers in the electrolyte,which results in the increase of channels available for Li^(+) diffusion.Thus,three-dimensional diffusion with high Li^(+) diffusion coefficient occurs in HE electrolytes.Furthermore,the anion-rich solvation structures promote the formation of the inorganic-rich SEI.As a result,over 2000 h of reversible Li plating/stripping with a low overpotential less than 27 mV is achieved in Li||Li cell using electrolyte modified by high-entropy strategy.Besides,the Li||LFP full cell with a negative capacity/positive capacity (N/P) ratio of 4.52 exhibits remarkably enhanced cycling stability,retaining 83.6% of its initial capacity after 150 cycles.This strategy offers a novel approach for accelerating Li^(+) transport kinetics and constructing stable SEI in lithium metal batteries.

Three-Dimensional Multi-Phase Microscopic Simulation of Service Life of Recycled Large Aggregate Self-Compacting Concrete

Recycled large aggregate self-compacting concrete (RLA-SCC) within multiple weak areas. These weak areas have poor resistance to chloride ion erosion, which affects the service life of RLA-SCC in the marine environment. A three-dimensional multi-phase mesoscopic numerical model of RLA-SCC was established to simulate the chloride ions transportation in concrete. Experiments of RLA-SCC immersing in chloride solution were carried out to verify the simulation results. The effects of recycled large aggregate (RLA) content and RLA particle size on the service life of concrete were explored. The results indicate that the mesoscopic numerical simulation results are in good agreement with the experimental results. At the same depth, the closer to the surface of the RLA, the greater the chloride ion concentration. The service life of RLA-SCC in marine environment decreases with the increase of RLA content. Compared with the service life of 20% content, the service life of 25% and 30% content decreased by 20% and 42% respectively. Increasing the particle size of RLA can effectively improve the service life of RLA-SCC in chloride environment. Compared with the service life of 50 mm particle size, the service life of 70 mm and 90 mm increased by 61% and 163%, respectively. .

Effect of Fly Ash on Frost-Resistance and Chloride Ions Diffusion Properties of Marine Concrete

It is necessary to pay more attention to the durability of concrete undergoing freeze-thaw cycles and seawater attack simultaneously.Investigated are the effects of water-binder ratio,fly ash（FA）contents and air-entraining agent on resistance to frost and chloride diffusion of marine concrete blended with FA in natural seawater.The results show that fly ash does not improve the frost resistance of concrete but can improve its resistance to chloride diffusion by addition of less than 30%.The resistance to frost and chloride diffusion of FA concrete can be improved with the decrease of water-binder ratio,and FA may improve both of them simultaneously only being mixed with air-entraining agent.A ratio（named as R）of the frost-resisting durability factor to chloride diffusion coefficient can be used to evaluate the durability of marine concrete.Scanning electron microscope（SEM）analyses are consistent with the evaluations by the value of R.

Fast ion diffusion alloy layer facilitating 3D mesh substrate for dendrite-free zinc-ion hybrid capacitors

Although aqueous zinc ion hybrid capacitors have advantageous integration of batteries and supercapacitors,they still suffer from the inherent problems of dendrite growth and interfacial side reactions on Zn anodes.Herein,a universal fast zinc-ion diffusion layer on a three-dimensional(3 D)mesh structure model is demonstrated to effectively improve Zn plating/stripping reversibility.The fast ion diffusion alloy layer accelerates the Zn^(2+)migration in an orderly manner to homogenize Zn^(2+)flux and overcomes the defects of the commercial mesh substrate,effectively avoiding dendrite growth and side reactions.Consequently,the proof-of-concept silver-zinc alloy modified stainless steel mesh delivers superb reversibility with the high coulombic efficiency over 99.4%at 4 mA cm^(-2)after 1600 cycles and excellent reliability of over 830 h at 1 mA cm^(-2),Its feasibility is also evidenced in commercial zinc ion hybrid capacitors with activated carbon as the cathode.This work enriches the fundamental comprehension of fast zinc-ion diffusion layer combined with a 3 D substrate on the Zn deposition and opens a universal approach to design advanced host for Zn electrodes in zinc ion hybrid capacitors.

Architecture engineering of carbonaceous anodes for high-rate potassium-ion batteries

The limited lithium resource in earth's crust has stimulated the pursuit of alternative energy storage technologies to lithium-ion battery.Potassium-ion batteries(KIBs)are regarded as a kind of promising candidate for large-scale energy storage owing to the high abundance and low cost of potassium resources.Nevertheless,further development and wide application of KIBs are still challenged by several obstacles,one of which is their fast capacity deterioration at high rates.A considerable amount of effort has recently been devoted to address this problem by developing advanced carbonaceous anode materials with diverse structures and morphologies.This review presents and highlights how the architecture engineering of carbonaceous anode materials gives rise to high-rate performances for KIBs,and also the beneficial conceptions are consciously extracted from the recent progress.Particularly,basic insights into the recent engineering strategies,structural innovation,and the related advances of carbonaceous anodes for high-rate KIBs are under specific concerns.Based on the achievements attained so far,a perspective on the foregoing,and proposed possible directions,and avenues for designing high-rate anodes,are presented finally.

Engineering Sodium Metal Anode with Sodiophilic Bismuthide Penetration for Dendrite-Free and High-Rate Sodium-Ion Battery

Sodium(Na)metal batteries with a high volumetric energy density that can be operated at high rates are highly desirable.However,an uneven Na-ion migration in bulk Na anodes leads to localized deposition/dissolution of sodium during high-rate plating/stripping behaviors,followed by severe dendrite growth and loose stacking.Herein,we engineer the Na hybrid anode with sodiophilic Na_(3)Bi-penetration to develop the abundant phase-boundary ionic transport channels.Compared to intrinsic Na,the reduced adsorption energy and ion-diffusion barrier on Na_(3)Bi ensure even Na^(+)nucleation and rapid Na^(+)migration within the hybrid electrode,leading to uniform deposition and dissolution at high current densities.Furthermore,the bismuthide enables compact Na deposition within the sodiophilic framework during cycling,thus favoring a high volumetric capacity.Consequently,the obtained anode was endowed with a high current density(up to 5 mA∙cm^(−2)),high areal capacity(up to 5 mA∙h∙cm^(−2)),and long-term cycling stability(up to 2800 h at 2 mA∙cm^(−2)).

Controllable synthesis of high loading LiFePO_4/C nanocomposites using bimodal mesoporous carbon as support for high power Li-ion battery cathodes

Mesoporous LiFePO4/C composites containing 80 wt% of highly dispersed LiFePO4 nanoparticles(4-6 nm) were fabricated using bimodal mesoporous carbon(BMC) as continuous conductive networks. The unique pore structure of BMC not only promises good particle connectivity for LiFePO4, but also acts as a rigid nano-confinement support that controls the particle size. Furthermore, the capacities were investigated respectively based on the weight of LiFePO4 and the whole composite. When calculated based on the weight of the whole composite, it is 120 mAh·g-1at 0.1 C of the high loading electrode and 42 mAh·g-1at 10 C of the low loading electrode. The electrochemical performance shows that high LiFePO4 loading benefits large tap density and contributes to the energy storage at low rates, while the electrode with low content of LiFePO4 displays superior high rate performance, which can mainly be due to the small particle size, good dispersion and high utilization of the active material, thus leading to a fast ion and electron diffusion.

Cellular Automata-based Chloride Ion Diffusion Simulation of Concrete Bridges under Multi-factor Coupling Actions

In order to accurately simulate the diffusion of chloride ion in the existing concrete bridge and acquire the precise chloride ion concentration at given time, a cellular automata （CA）-based model is proposed. The process of chloride ion diffusion is analyzed by the CA-based method and a nonlinear solution of the Fick＇s second law is obtained. Considering the impact of various factors such as stress states, temporal and spatial variability of diffusion parameters and water-cement ratio on the process of chloride ion diffusion, the model of chloride ion diffusion under multi-factor coupling actions is presented. A chloride ion penetrating experiment reported in the literature is used to prove the effectiveness and reasonability of the present method, and a T-type beam is taken as an illustrative example to analyze the process of chloride ion diffusion in practical application. The results indicate that CA-based method can simulate the diffusion of chloride ion in the concrete structures with acceptable precision.

Durability of sea-sand containing concrete:Effects of chloride ion penetration

This paper describes an orthogonal experiment on the effect of water/cement ratio,water consumption per cubic meter,curing time,and type of sand on the response＂resistance to chloride ion penetration＂.A sea-sand containing concrete was used for the trials.An analysis of chloride ion diffusion coefficients at different factor levels was performed.A predictive model of chloride ion diffusion in concrete is developed through regression analysis.The experimental results show that when the water/cement ratio varies from 0.45 to 0.60,and the water consumption per cubic meter varies from 185 to 215 kg,and the curing time varies from 30 to 180 d then the size of the effects fall in the order（most significant first）： curing time,type of sand,water consumption per cubic meter,and water/cement ratio.Chloride ion penetration is reduced,and better durability of the concrete is observed,with longer curing times,less water consumption per cubic meter,and a smaller water/cement ratio.

Strength and Chloride Diffusion Behaviour of Three Generations of Repeated Recycled Fine Aggregate Concrete

The feasibility of using different generations of recycled fine aggregate（RFA） in structural concrete in a chloride environment was evaluated by studying the performance of the RFA and the corresponding concrete. The different generations of RFA were recycled by following the cycle of ‘concrete-waste concrete-fine aggregate-concrete＇. The properties of three generations of repeatedly recycled fine aggregate（RRFA） were systematically investigated, and we focused on the compressive strength and splitting tensile strength and chloride ion permeability of the related structural concretes with 25%, 75%, and 100% replacement of natural fine aggregates with RFA. The results indicated that the quality of RRFA presents a trend of slow deterioration, but the overall performance of all RRFA still fulfils the quality requirements of recycled fine aggregate for structural concrete. All RRFA concretes achieved the target compressive strength of 40 MPa after 28 days except for the second generation of the recycled aggregate concrete and the third generation of the recycled aggregate concrete with 100% replacement, and all the concrete mixes achieved the target compressive strength after 90 days. The insights obtained in this study demonstrate the feasibility of using at least three generations of RRFA for the production of normal structural concrete with a design service life of 100 years in a chloride environment.

Implanting a preferential solid electrolyte interphase layer over anode electrode of lithium ion batteries for highly enhanced Li^+ diffusion properties

The lithium-ion batteries are recognized as the most promising energy storage system,but it still does not meet the power requirements of electric vehicle batteries owing to low volumetric energy density with the traditional graphite electrode system.In this study,we report the development of a novel electrode system fabricated by implantation of a solid electrolyte interphase(SEI)layer on the graphite surface.The SEI-implanted graphite electrode is made using a lithium bis(trifluoromethanesulfonyl)imide(LiTFSI)-based electrolyte and cycled with a lithium tetrafluoroborate LiBF4-based electrolyte.This new electrode system shows significantly enhanced electrochemical properties owing to the rapid and efficient diffusion of Li ions through the SEI layer between the electrolyte and electrode.This graphite electrode with its pre-formed SEI layer achieves a reversible capacity of 357 mAh g^-1 at 0.5 C after 50 cycles,which is significantly higher than that of commercial lithium-ion battery systems constructed with LiPF6(312mAh g^-1).The resulting unique electrode system could present a new avenue in SEI research for highperformance lithium-ion batteries.

Water molecules and oxygen-vacancy modulation of vanadium pentoxide with fast kinetics toward ultrahigh power density and durable flexible all-solid-state zinc ion battery

Aqueous zinc ion battery(ZIB)with many virtues such as high safety,cost-effective,and good environmental compatibility is a large-scale energy storage technology with great application potential.Nevertheless,its application is severely hindered by the slow diffusion of zinc ions in desirable cathode materials.Herein,a technique of water-incorporation coupled with oxygen-vacancy modulation is exploited to improve the zinc ions diffusion kinetics in vanadium pentoxide(V_(2)O_5)cathode for ZIB.The incorporated water molecules replace lattice oxygen in V_(2)O_5,and function as pillars to expand interlayer distance.So the structural stability can be enhanced,and the zinc ions diffusion kinetics might also be promoted during the repeated intercalation/deintercalation.Meanwhile,the lattice water molecules can effectively enhance conductivity due to the electronic density modulation effect.Consequently,the modulated V_(2)O_5(H-V_(2)O_5)cathode behaves with superior rate capacity and stable durability,achieving 234 mA h g^(-1)over 9000 cycles even at 20 A g^(-1).Furthermore,a flexible all-solid-state(ASS)ZIB has been constructed,exhibiting an admirable energy density of 196.6 Wh kg^(-1)and impressive power density of 20.4 kW kg^(-1)as well as excellent long-term lifespan.Importantly,the assembled flexible ASS ZIB would be able to work in a large temperature span(from-20 to 70℃).Additionally,we also uncover the energy storage mechanism of the H-V_(2)O_5 electrode,offering a novel approach for creating high-kinetics cathodes for multivalent ion storage.

A Time-saving Method for Assessing the Corrosion Inhibitor Efficiency

Corrosion inhibitor is one of the most important technologies to enhance the durability of steel reinforced concrete. A kind of time-saving method was developed to assess the inhibitor efficiency by using a 16 voltage electric field to accelerate the chloride ion diffusion in concrete and inducing corrosion. Both macrocell and microcell current measurements were used to confirm the corrosion initiation status of steel. The comprehensive efficiency of inhibitor shall be assessed in three aspects. The results clearly show the efficiency of different inhibitors, which indicate the reliability of this time-saving method.

Durability of Reinforced Concrete Structures under Coupling Action of Load and Chlorine Erosion

Diffusion behavior of chloride ion in reinforced concrete under bendingmoment was studied by taking the ratio of bending moment to ultimate flexural capacity asload level indicator. The function relationship between load level and chloride iondiffusion coefficient was established, based on that the limit state equation of the chlorideion critical concentration and chloride ion concentration on surface of the steel bar wasestablished. Then by applying Monte-Carlo method the corrosion probability ofreinforcement under different load levels in splash zone was calculated. Calculation resultsdemonstrated that compared with the durability reliability index considering loading effect,the reliability index without considering loading effect could be 100% higher. Inconsideration of requirement for concrete durability, some revision suggestion was putforward. It was recommended that for beam members with different design life in splashzone, the corresponding minimum cover thickness should be adjusted properly as well aswater-cement ratio limit.

Three-dimensional Li-ion transportation in Li_(2)MnO_(3)-integrated LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)

Ni-rich layered cathodes(LiNi_xCo_yMn_(2)O_(2))have recently drawn much attention due to their high specific capacities.However,the poor rate capability of LiNi_xCo_yMn_(2)O_(2),which is mainly originated from the twodimensional diffusion of Li ions in the Li slab and Li^(+)/Ni^(2+)cation mixing that hinder the Li^(+)diffusion,has limited their practical application where high power density is needed.Here we integrated Li_(2)MnO_(3)nanodomains into the layered structure of a typical Ni-rich LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)material,which minimized the Li^(+)/Ni^(2+)cationic disordering,and more importantly,established grain boundaries within the NCM811 matrix,thus providing a three-dimensional diffusion channel for Li ions.Accordingly,an average Li-ion diffusion coefficient(D_(Li+))of the Li_(2)MnO_(3)-integrated LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811-I)during charge/discharge was calculated to be approximately 6*10^(-10)cm~2 S^(-1),two times of that in the bare NCM811(3*10^(-10)cm~2 S^(-1)).The capacity delivered by the NCM811-I(154.5 mAh g^(-1))was higher than that of NCM811(141.3 mAh g^(-1))at 2 C,and the capacity retention of NCM811-I increased by 13.6%after100 cycles at 0.1 C and 13.4%after 500 cycles at 1 C compared to NCM811.This work provides a valuable routine to improve the rate capability of Ni-rich cathode materials,which may be applied to other oxide cathodes with sluggish Li-ion transportation.

Effects of temperature variation on Li_xFe PO_4/C(0

Li Fe PO4/C was prepared via solid state reaction and characterized with X-ray powder diffraction and charge–discharge test. As-prepared Li Fe PO4/C has a triphylite structure and exhibits an excellent rate capability and capacity retention. Electrochemical impedance spectroscopy(EIS) was applied to investigate LixFe PO4/C(0<x<1) electrode on temperature variation. The valid equivalent circuit for EIS fitting was determined which contains an intercalation capacitance for Li+ ion accumulation and consumption in the electrode reaction. The surface layer impedance needs to be included in the equivalent circuit when Li Fe PO4/C is deeply delithiated at a relatively high temperature. EIS examination indicates that a temperature rise leads to a better reversibility, lower charge transfer resistance, higher exchange current density J0 and greater Li+ ion diffusion coefficient for the LixFe PO4/C electrode process. The Li+ ion concentration in LixFe PO4/C is potential to impact the Li+ ion diffusion coefficient, and a decrease in the former results in an increase in the latter.

Phase Transition and Oxygen Ion Diffusion in （La1-xLnx）2Mo2O9 （Ln=Nd, Gd, x=0.05-0.25） Using Dielectric Relaxation Method

Dielectric relaxation method was employed to study the properties of oxygen ion diffusion and phase transition in the oxide-ion conductors （Lal-xLnx）2Mo209 （Ln=Nd, Gd, x=0.05-0.25）. Two dielectric loss peaks were observed： peak Pd at about 600 K and peak P5 around 720 K. Peak Pd is a relaxational peak and associated with the short-range diffusion of oxygen ions, while peak P5 hardly changes its position and dramatically decreases in height with increasing frequency, exhibiting non-relaxational nature. With increasing Ln^3＋ concentration, the heights of peak Ph and Pd increase at first and then decrease after passing a maximum at 15% doping. It is suggested that peak P5 is related to the phase transition of a static disordered state to a dynamic disordered state in oxygen ions/vacancies distribution. It is found that the 15%Gd or 15%Nd doped La2Mo209 samples exhibit the highest conductivity in accordance with the highest height of peak Pd at this doping content.

Corrosion life of artificial reef under natural seawater conditions

Corrosion of steel bars with chloride salt erosion is one of the main reasons for the deterioration of the performance of reinforced concrete structures.The key to the service life of concrete members is the transport rate of chloride ions and the time for rusting of steel bars.In this paper,the artificial reef concrete member is taken as the research object,and the diffusion coefficient of seawater chloride ion in C30,C35 and steel slag composite artificial reef concrete is analyzed.The critical chloride ion concentration of steel corrosion in concrete is used as the boundary condition for life prediction.The chloride ion diffusion model predicts the corrosion life of C30,C35 and steel slag composite artificial reefs in seawater.The results show that the diffusion law of chloride ions in concrete artificial reefs basically meets Fick's second law.The corrosion life of C30,C35 and steel slag composite concrete reefs was calculated by the model to be 51.6,54.8 and 56.8 years,respectively.