Lithiophilicity: The key to efficient lithium metal anodes for lithium batteries

Lithium metal anode of lithium batteries,including lithium-ion batteries,has been considered the anode for next-generation batteries with desired high energy densities due to its high theoretical specific capacity(3860 mA h g^(-1))and low standards electrode potential(-3.04 V vs.SHE).However,the highly reactive nature of metallic lithium and its direct contact with the electrolyte could lead to severe chemical reactions,leading to the continuous consumption of the electrolyte and a reduction in the cycle life and Coulombic efficiency.In addition,the solid electrolyte interface formed during battery cycling is mainly inorganic,which is too fragile to withstand the extreme volume change during the plating and stripping of lithium.The uneven flux of lithium ions could lead to excessive lithium deposition at local points,resulting in needle-like lithium dendrites,which could pierce the separator and cause short circuits,battery failure,and safety issues.In the last five years,tremendous efforts have been dedicated to addressing these issues,and the most successful improvements have been related to lithiophilicity optimizations.Thus,this paper comprehensively reviewed the lithiophilicity regulation in lithium metal anode modifications and highlighted the vital effect of lithiophilicity.The remaining challenges faced by the lithiophilicity optimization for lithium metal anodes are discussed with the proposed research directions for overcoming the technical challenges in this subject.

Ternary Ni-based Prussian blue analogue with superior sodium storage performance induced by synergistic effect of Co and Fe

Prussian blue analogue Na2Ni[Fe(CN)6](Ni-PB)has been widely studied as a cathode material for sodium-ion battery due to its excellent cycling performance.However,Ni-PB has a low theoretical capacity of 85 mAh g^(−1) because of the electrochemical inertness of Ni.Herein,ternary Ni-PB is successfully synthesized by double doping with Co and Fe at Ni-site,and the effect of doping with Co and Fe on the electrochemical performance of Ni-PB is systematically investigated through theoretical calculations and electrochemical tests.The first principles calculations confirm that double doping with Co and Fe can significantly reduce the energy barrier and bandgap of Ni-PB.X-ray diffraction and composition analysis results indicate that ternary NiCoFe-PB composite not only has good crystallinity and high Na content but also has low defects and crystal water.Electrochemical tests reveal that,besides the capacity contribution of high-spin Co/Fe and low-spin Fe,Co-doping enhances the electrochemical activity of low-spin Fe and Fe-doping improves the activity of high-spin Co;moreover,double doping can decrease the diffusion resistance of Na+ions through solid electrolyte interface film,accelerate the kinetics for both ion diffusion process and Faradic reaction,and increase active sites.Under the synergistic effect of Co and Fe,this ternary NiCoFe-PB exhibits outstanding electrochemical performance with a high initial discharge capacity of 120.4 mAh g^(−1) at 20mA g^(−1) and an extremely low capacity fading rate of 0.0044%per cycle at a high current density of 2 A g^(−1) even after 10,000 cycles,showing great application potential of ternary NiCoFe-PB in the field of large-scale energy storage.

Metallic phase W_(0.9)Mo_(0.1)S_(2)for high-performance anode of sodium ion batteries through suppressing the dissolution of polysulfides

WS_(2)with layered graphite-like structure as anode for sodium ion batteries has high specific capacity.However,the poor cycling performance and rate capability of WS_(2)caused by the low electronic conductivity and structure changes during cycles inhibit its practical application.Herein,metallic phase(1T)W_(x)Mo_(1−x)S2(x=1,0.9,0.8 and 0.6)with high electronic conductivity and expanded interlayer spacing of 0.95 nm was directly prepared via a simple hydrothermal method.Specially,1T W_(0.9)Mo_(0.1)S_(2)as anode for sodium ion batteries displays high capacities of 411 mAh g^(-1)at 0.1 A g^(-1)after 180 cycles and 262 mAh g^(-1)at 1 A g^(-1)after 280 cycles and excellent rate capability(245 mAh g^(-1)at 5 A g^(-1)).The full cell based on Na_(3)V_(2)(PO_(4))_(2)O_(2)F/C cathode and 1T W_(0.9)Mo_(0.1)S_(2)anode also exhibits high capacity and good cycling performance.The irreversible electrochemical reaction of 1T W_(0.9)Mo_(0.1)S_(2)with Na ions during first few cycles results in the main products of W-Mo alloy and S.The strong adsorption of W-Mo alloy with polysulfides can effectively suppress the dissolution and shuttle effect of polysulfides,which ensures the excellent cycling performance of 1T W_(0.9)Mo_(0.1)S_(2).

Dielectric polarization in MgFe_(2)O_(4) coating and bulk doping to enhance high-voltage cycling stability of Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2) cathode material

Charging P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)to 4.5 V for higher capacity is enticing.However,it leads to severe capacity fading,ascribing to the lattice oxygen evolution and the P2-O2 phase transformation.Here,the Mg Fe_(2)O_(4) coating and Mg,Fe co-doping were constructed simultaneously by Mg,Fe surface treatment to suppress lattice oxygen evolution and P2-O2 phase transformation of P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)at deep charging.Through ex-situ X-ray diffraction(XRD)tests,we found that the Mg,Fe bulk co-doping could reduce the repulsion between transition metals and Na+/vacancies ordering,thus inhibiting the P2-O2 phase transition and significantly reducing the irreversible volume change of the material.Meanwhile,the internal electric field formed by the dielectric polarization of Mg Fe_(2)O_(4) effectively inhibits the outward migration of oxidized O^(a-)(a<2),thereby suppressing the lattice oxygen evolution at deep charging,confirmed by in situ Raman and ex situ XPS techniques.P2-Na NM@MF-3 shows enhanced high-voltage cycling performance with capacity retentions of 84.8% and 81.3%at 0.1 and 1 C after cycles.This work sheds light on regulating the surface chemistry for Na-layered oxide materials to enhance the high-voltage performance of Na-ion batteries.

Achieving a superior Na storage performance of Fe-based Prussian blue cathode by coating perylene tetracarboxylic dianhydride amine

Fe-based Prussian blue(Fe-PB)cathode material shows great application potential in sodium(Na)-ion batteries due to its high theoretical capacity,long cycle life,low cost,and simple preparation process.However,the crystalline water and vacancies of Fe-PB lattice,the low electrical conductivity,and the dissolution of metal ions lead to limited capacity and poor cycling stability.In this work,a perylene tetracarboxylic dianhydride amine(PTCDA)coating layer is successfully fabricated on the surface of Fe-PB by a liquid-phase method.The aminated PTCDA(PTCA)coating not only increases the specific surface area and electronic conductivity but also effectively reduces the crystalline water and vacancies,which avoids the erosion of Fe-PB by electrolyte.Consequently,the PTCA layer reduces the charge transfer resistance,enhances the Na-ion diffusion coefficient,and improves the structure stability.The PTCA-coated Fe-PB exhibits superior Na storage performance with a first discharge capacity of 145.2 mAh g^(−1) at 100 mA g^(−1).Long cycling tests exhibit minimal capacity decay of 0.027%per cycle over 1000 cycles at 1 A g^(−1).Therefore,this PTCA coating strategy has shown promising competence in enhancing the electrochemical performance of Fe-PB,which can potentially serve as a universal electrode coating strategy for Na-ion batteries.

A Novel 3D Pillar-layered Co(Ⅱ)-MOF with(4,8)-Connected Topology:Synthesis,Structure and Magnetic Properties

By using "pillaring" strategy, a new Co(Ⅱ)-MOF, [Co_2(abtc)(bimb)_2]·2H_2O(1, H_4abtc = 3,3?,5,5?-azobenzenetetracarboxylic acid, bimb = 4,4?-bis(imidazole-1-ylmethyl)biphenyl), has been solvothermally synthesized and structurally characterized. The structural determination revealed that 1 features a 3D pillar-layered framework with(4,8)-connected {4~4.6~2}{4~8.6^(20)} topology based on dinuclear Co(Ⅱ)-SBUs. The magnetic investigation shows that the dominant antiferromagnetic coupling is observed in compound 1.

Probability distribution of wind power volatility based on the moving average method and improved nonparametric kernel density estimation

In the process of large-scale,grid-connected wind power operations,it is important to establish an accurate probability distribution model for wind farm fluctuations.In this study,a wind power fluctuation modeling method is proposed based on the method of moving average and adaptive nonparametric kernel density estimation(NPKDE)method.Firstly,the method of moving average is used to reduce the fluctuation of the sampling wind power component,and the probability characteristics of the modeling are then determined based on the NPKDE.Secondly,the model is improved adaptively,and is then solved by using constraint-order optimization.The simulation results show that this method has a better accuracy and applicability compared with the modeling method based on traditional parameter estimation,and solves the local adaptation problem of traditional NPKDE.

Two Ni^Ⅱ/Cu^Ⅱ Coordination Polymers Based on Pyridyl-carboxylate Ligand:Synthesis,Crystal Structures and Magnetic Properties

Under hydrothermal conditions, the reactions of Ni~Ⅱ/Cu~Ⅱ ions with 3-(6-aminpyridinium-3-yl) benzoate(HL) afford two compounds [NiL 2]n(1) and [Cu L2(H2 O)]n(2). On the basis of X-ray diffraction analysis of the two compounds, the results show that compound 1 features one-dimensional(1 D) double-strand coordination arrays, while 2 presents the 63-hcb layers. Both compounds are further constructed into a 3 D supramolecular structure with the aid of weak secondary interactions. Thermal stabilities and magnetic properties of compounds 1 and 2 were also investigated.

ClO_4^--directed Assembly of Two Co^ⅡComplexes Based on Flexible N-donor Ligands:Syntheses,Crystal Structures and Magnetic Properties

The reaction of Co^II ions with 1,4-bis(imidazol)butane(bimb) or 1,4-bis(triazol)butane(bitb) in the presence of ClO_4^-, respectively affords two CoII coordination complexes, namely {[Co(bimb)_3]·2ClO_4}n(I) and {[Co(bitb)_3]·2ClO_4}n(II). Single-crystal X-ray analysis indicates that both complexes I and II show the same α-Po topological structures. However, complex I exhibits a 2-fold interpenetrating network, while complex II features a 3-fold interpenetrating network. In addition, solid-state properties such as thermal stabilities and magnetic properties of two complexes were also investigated.

Doped, conductive SiO_(2) nanoparticles for large microwave absorption

Although many materials have been studied for the purpose of microwave absorption,SiO_(2) has never been reported as a good candidate.In this study,we present for the first time that doped,microwave conductive SiO_(2) nanoparticles can possess an excellent microwave absorbing performance.A large microwave reflection loss(RL)of−55.09 dB can be obtained.The large microwave absorption originates mainly from electrical relaxation rather than the magnetic relaxation of the incoming microwave field.The electrical relaxation is attributed to a large electrical conductivity that is enabled by the incorporation of heterogeneous(N,C and Cl)atoms.The removal of the magnetic susceptibility only results in a negligible influence of the microwave absorption.In contrast,the removal of the heterogeneous atoms leads to a large decrease in the electrical conductivity and microwave absorption performance.Meanwhile,the microwave absorption characteristics can be largely adjusted with a change of the thickness,which provides large flexibility for various microwave absorption applications.

In situ formation of ionically conductive nanointerphase on Si particles for stable battery anode

Silicon(Si)is a promising anode candidate for next-generation lithium-ion batteries(LIBs)due to its high theoretical capacity.Solar Si photovoltaic waste possesses good purity and high output.Using it as the raw material for battery anodes can synchronously solve the problem of solid waste pollution and enable high energy density LIBs.A critical issue impeding the practical application of Si is the undesirable side reactions at the electrolyte-particle interface and the resulting increase in impedance during cycling.Herein,a Si-P core shell structure with chemical bonding at the Si-P interface is fabricated through a simple mechanical alloying reaction between red P and solar Si photovoltaic waste.The P nanoshell with thickness within 15 nm converts to Li3P during the initial lithiation process and maintains its phase on cycling.The as-formed Li3P nanolayer functions as a stable,ionically conductive protective layer that reduces the direct contact between Si and electrolytes,and thus suppresses undesired side reactions.The Si-P nanocomposite exhibits stable electrochemical cycling with a high reversible capacity of 1,178 mAh g^(−1)after 500 cycles at 1,200 mA g^(−1),as well as excellent rate capability(912 mAh g^(−1)at 2 C).With 15 wt%addition to graphite,a graphite/Si-P hybrid electrode shows a high overall reversible specific capacity of 447 mAh g^(−1)and 88.3%capacity retention after 100 cycles at high areal capacity of 2.64 mAh cm^(−2) at 100 mA g^(−1),indicating its promise as a drop-in anode in practical LIBs.

Structure and defect dual-engineering of cobalt oxides for lowtemperature Zn-air batteries

The exploration of bifunctional electrocatalysts with high catalytic activity and long-term durability for low-temperature Zn-air batteries(ZABs)is an ongoing challenge.Here,quintet-shelled hollow spheres,P-doped multi-layer Co_(3)O_(4)(PM-Co_(3)O_(4)),with enriched oxygen vacancies are prepared by thermally induced mass relocation and a simple phosphating process.Various advanced characterizations reveal P anion-induced effects on internal electronic structure and local coordination environment.The finite element method elucidates that the complex multi-layer spherical nanostructure is conducive to the transport and diffusion of OH-and O_(2).Benefiting from its unique structural features and abundant oxygen vacancies,the well-designed PM-Co_(3)O_(4) presents small reversible oxygen overpotential for catalyzing oxygen reduction/evolution reactions.Accordingly,the fabricated low-temperature ZABs based on PM-Co_(3)O_(4) as air-cathode exhibit high power density(20.8 mW·cm^(-2))and long-term stability(over 600 cycles)at the ultra-low temperature of-40℃,outperforming state-of-art Pt/C+IrO_(2)-based ZABs.Furthermore,the dynamic evolution mechanism of cobalt oxide catalysts during ZAB operation is elucidated.This work provides a guideline to design efficient electrocatalysts with regulated electronic configurations and exquisite nano-/microstructures for ZABs under extreme working conditions.

Synthesis,properties,and applications of black titanium dioxide nanomaterials

Photocatalysis has been regarded as one of best solutions to using the sunlight to produce hydrogen from water and to removing organic pollutants from the environment,and titanium dioxide(TiO_22) nanomaterials have been treated as the primary photocatalyst for these purposes. However,their large band gap has largely limited the activity to the UV region of the solar spectrum. The discovery of black TiO_2 n2011 has triggered world-wide research interests with new hope to overcome this problem. This review briefly summarizes the recent progresses of black TiO_2 nanomaterials,including their synthesis,properties and applications,to provide a timely update and to inspire more ideas in the related research.

Assembling of a novel 3D Ag(Ⅰ)-MOFs with mixed ligands tactics：Syntheses, crystal structure and catalytic degradation of nitrophenol

A silver-based metal-organic framework(Ag-MOFs), [Ag2(H3 ddcba)(dpp)2](1)(H5 ddcba = 3,5-(di(2',5'-dicarboxylphenyl)benozoic acid, dpp = 1,3-di(4-pyridyl)propane), was successfully constructed via hydrothermal assembly of a pentacaboxylate ligand, a N-donor ligand and Ag(I) ions, which possesses a pcu topology and exhibits excellent catalytic properties in aqueous solution for the degradation of onitrophenol(2-NP), m-nitrophenol(3-NP) and p-nitrophenol(4-NP). Related kinetics of such catalytic reactions, photoluminescent and thermal stability of compound 1 were also investigated.

Microwave absorption of aluminum/hydrogen treated titanium dioxide nanoparticles

Interactions between incident electromagnetic energy and matter are of critical importance for numerous civil and military applications such as photocatalysis,solar cells,optics,radar detection,communications,information processing and transport et al.Traditional mechanisms for such interactions in the microwave frequency mainly rely on dipole rotations and magnetic domain resonance.In this study,we present the first report of the microwave absorption of Al/H2 treated TiO_(2) nanoparticles,where the A_(l)/H_(2) treatment not only induces structural and optical property changes,but also largely improves the microwave absorption performance of TiO_(2) nanoparticles.Moreover,the frequency of the microwave absorption can be finely controlled with the treatment temperature,and the absorption efficiency can reach optimal values with a careful temperature tuning.A large reflection loss of
58.02 dB has been demonstrated with 3.1mm TiO_(2) coating when the treating temperature is 700℃.The high efficiency of microwave absorption is most likely linked to the disordering-induced property changes in the materials.Along with the increased microwave absorption properties are largely increased visiblelight and IR absorptions,and enhanced electrical conductivity and reduced skin-depth,which is likely related to the interfacial defects within the TiO_(2) nanoparticles caused by the Al/H2 treatment.

Absorption Enhancement of Ultrathin Crystalline Silicon Solar Cells with Dielectric Si3N4 Nanostructures

A design of ultrathin crystalline silicon solar cell with Si3 N4 circular truncated cone holes(CTCs)arrays on the top is proposed.In this article,we perform an optical simulation of the structure.The finite-difference time-domain method is used to calculate the optical absorption of different periods,radius of top and bottom circles and depth of Si3 N4 CTCs.The short-circuit current density generated by the optimized cells(30.17 mA/cm^2)is 32.44%more than the value gained by control group(with flat Si3 N4).Then adding a layer of back silver to allow us to better analyze optical absorption.Later,we simulate the optimization of the same configuration of different silicon thicknesses andfind that our structure does enhance the light absorption.This work uses a combined path towards achieving higher photocurrent ultrathin crystalline silicon solar cells by constructing the texture of anti-reflection coating.

Dendrite-free and stable Zn metal anodes with ZnO protective layer

Metallic Zn can be used as an anode for aqueous zinc-ion batteries due to its low redox potential,rich resources,and high theoretical capacity.However,its practical application is limited by dendrite growth and side reactions.Herein,a simple in-situ growth strategy was applied to fabricate a Zn anode with a ZnO protective layer(Zn/ZnO)to lengthen the cycle life and inhibit the dendrite growth and side reactions.At 1 mA h cm^(−2)capacity,Zn/ZnO exhibits long-time stability(2500 h)at 1 mA cm^(−2)and outstanding rate capability(1000 h at 10 mA cm^(−2))in symmetrical cells.Furthermore,the average coulombic efficiency of the Zn/ZnO//Ti cell is 99.4%,which is desirable at 5 mA cm^(−2).In addition,the Zn/ZnO//MnO_(2)cell can maintain a specific capacity of 167.2 mA h g^(−1)after 800 stable cycles.This work presents a simple fabrication method for Zn anode with excellent performance and suggests the huge possibilities of implementing practically rechargeable aqueous zinc-ion batteries.

Breakdown of Valence Shell Electron Pair Repulsion Theory in an H-Bond-Stabilized Linear sp-Hybridized Sulfur

Exploring the unusual orbital hybridization types of atoms and their new connection modes contributes to the development of chemical bond theory and can inspire compounds with unique molecular configurations.Dicoordinated sulfur(S)atoms(or anions)with sp3 hybridization in a bent-bridging mode are commonly observed in many inorganic and organic compounds.However,sp-hybridized S species have,thus far,been extremely rare,and the linearly bridging mode has only been“forcibly”achieved with the aid of metal–S multiple bonds and/or significant steric hindrance from the surrounding organic ligands.