Crystalline and amorphous metal sulfide composite electrode materials with long cycle life:Preparation and performance of hybrid capacitors

Crystalline@amorphous NiCo_(2)S_(4)@MoS_(2)(v-NCS@MS)nanostructures were designed and constructed via an ethylene glycol-induced strategy with hydrothermal synthesis and solvothermal method,which simultaneously realized the defect regulation of crystal NiCo_(2)S_(4) in the core.Taking advantage of the flexible protection of an amor-phous shell and the high capacity of a conductive core with defects,the v-NCS@MS electrode exhibited high specif-ic capacity(1034 mAh·g^(-1) at 1 A·g^(-1))and outstanding rate capability.Moreover,a hybrid supercapacitor was assembled with v-NCS@MS as cathode and activated carbon(AC)as anode,which can achieve remarkably high specific energy of 111 Wh·kg^(-1) at a specific power of 219 W·kg^(-1) and outstanding capacity retention of 80.5%after 15000 cycling at different current densities.

Elastic Buffering Layer on CuS Enabling High-Rate and Long-Life Sodium-Ion Storage

The latest view suggests the inactive core,surface pulverization,and poly sulfide shuttling effect of metal sulfides are responsible for their low capacity and poor cycling performance in sodium-ion batteries(SIBs).Whereas overcoming the above problems based on conventional nanoengineering is not efficient enough.In this work,erythrocyte-like CuS microspheres with an elastic buffering layer of ultrathin poly aniline(PANI) were synthesized through one-step selfassembly growth,followed by in situ polymerization of aniline.When CuS@PANI is used as anode electrode in SIBs,it delivers high capacity,ultrahigh rate capability(500 mAh gat 0.1 A g,and 214.5 mAh gat 40 A g),and superior cycling life of over 7500 cycles at 20 A g.A series of in/ex situ characterization techniques were applied to investigate the structural evolution and sodium-ion storage mechanism.The PANI swollen with electrolyte can stabilize solid electrolyte interface layer,benefit the ion transport/charge transfer at the PANI/electrolyte interface,and restrain the size growth of Cu particles in confined space.Moreover,finite element analyses and density functional simulations confirm that the PANI film effectively buffers the volume expansion,suppresses the surface pulverization,and traps the poly sulfide.

Amorphous phosphorus chalcogenide as an anode material for lithiumion batteries with high capacity and long cycle life

The ever-increasing demands for modern energy storage applications drive the search for novel anode materials of lithium(Li)-ion batteries(LIBs) with high storage capacity and long cycle life, to outperform the conventional LIBs anode materials. Hence, we report amorphous ternary phosphorus chalcogenide(aP_(4)SSe_(2)) as an anode material with high performance for LIBs. Synthesized via the mechanochemistry method, the a-P_(4)SSe_(2) compound is endowed with amorphous feature and offers excellent cycling stability(over 1500 mA h g^(-1) capacity after 425 cycles at 0.3 A g^(-1)), owing to the advantages of isotropic nature and synergistic effect of multielement forming Li-ion conductors during battery operation. Furthermore,as confirmed by ex situ X-ray diffraction(XRD) and transmission electron microscope(TEM), the a-P_(4)SSe_(2)anode material has a reversible and multistage Li-storage mechanism, which is extremely beneficial to long cycle life for batteries. Moreover, the autogenous intermediate electrochemical products with fast ionic conductivity can facilitate Li-ion diffusion effectively. Thus, the a-P_(4)SSe_(2)electrode delivers excellent rate capability(730 mA h g^(-1)capacity at 3 A g^(-1)). Through in situ electrochemical impedance spectra(EIS) measurements, it can be revealed that the resistances of charge transfer(R_(SEI)) and solid electrolyte interphase(R_(Ct)) decrease along with the formation of Li-ion conductors whilst the ohmic resistance(R_(Ω)) remains unchanged during the whole electrochemical process, thus resulting in rapid reaction kinetics and stable electrode to obtain excellent rate performance and cycling ability for LIBs. Moreover, the formation mechanism and electrochemical superiority of the a-P_(4)SSe_(2)phase, and its expansion to P_(4)S_(3-x)Se_(x)(x = 0, 1, 2, 3) family can prove its significance for LIBs.

Research on the Integration of Structural Design and Material Parameters of Long-life Asphalt Pavement

In order to reduce the disease risk stemming from asphalt concrete pavement and ensure the safety of road operation,we should pay attention to the structural design of long-life asphalt pavement,strengthen the selection of long-term pavement materials,scientifically set the pavement mechanical performance indexes based on the calculation results of pavement structure thickness combination and modulus combination,and ensure the stability and durability of road pavement structure through the real-time establishment of three-dimensional finite element calculation model,as well as the integrated design that takes into consideration the aspects of road subgrade,semi-rigid base and asphalt layer.

The Secrets of Long Life

Living to a ripe old age in China is on the increase - and a healthy lifestyle emerges as the key by Tang Yuankai SHE moves about with ease and sees and hears without any trouble.And on most days she climbs a mountain to work on

Manipulating Horizontal Zn Deposition with Graphene Interpenetrated Zn Hybrid Foils for Dendrite-Free Aqueous Zinc Ion Batteries

Aqueous zinc ion batteries(ZIBs)with intrinsic safety have great potentials in portable devices,but suffer from limited cycling life mainly caused by serious dendrite growth and unavoidable side reactions of Zn anodes.Herein,graphene interpenetrated Zn(GiZn)hybrid foils are developed for dendrite-free and long-term Zn anodes for high-performance ZIBs.The GiZn anode is prepared by interfacial assembly of reduced graphene oxide(rGO)on the skeletons of zinc foams,followed by mechanical compression into hybrid foils and drying process.The presence of the rGO nanosheets in the GiZn hybrid foils provides abundant zincophilic sites to induce horizontal Zn deposition for Zn metal anodes without the growth of dendrites.Meanwhile,the uniform distribution of rGO nanosheets endows the hybrid foils with superior conductivity and wetting ability with electrolytes for reduced interfacial resistances.As a result,GiZn-based symmetric cells exhibit a small voltage hysteresis of 30.4 mV and remarkable areal capacity of 30 mAh cm^(-2)at 0.5 mA cm^(-2).Further,GiZn anodes also enable the corresponding aqueous Zn||MnO_(2)batteries with high capacity of 168.5 mAh g^(-1)at 8 C,superior to the counterpart with pure Zn foil anodes(72.7 mAh g^(-1)).Therefore,GiZn hybrid foil anodes will shed light on the rational construction of 2D material-interpenetrated Zn hybrid foil anodes for high-performance ZIBs.

Towards storable and durable Zn-MnO_(2) batteries with hydrous tetraglyme electrolyte

Aqueous rechargeable zinc-based batteries have attracted increasing interest and been considered potential alternatives for state-of-the-art lithium-ion batteries because of the low cost and high safety.Many cathode materials have been gradually developed and demonstrated excellent electrochemical performances.However,the complex electrochemistry,inevitable hydrogen release,and zinc corrosion severely hinder the practical application.The most concerned Zn-MnO_(2)batteries still suffer from the Mn dissolution and formation of byproducts.By adding organic solvents to inhibit the activity of water molecules,the hydrous organic electrolytes provide a sound solution for eliminating the unfavorable factors.Here we report a tetraethylene glycol dimethyl ether-based hydrous organic electrolyte consisting of LiClO_(4)·3H_(2)O and Zn(ClO4)2·6H2O,and a birnessite-type MnO_(2)cathode material for Zn-MnO_(2)batteries.The Li+/Zn2+ions co-(de)insertion mechanism is ascertained by the structural and morphological analyses.The electrostatic interaction between inserted ions and crystal structure is reduced effectively by employment of monovalent Li+ions,which ensures structural stability of cathode materials.Hydrous tetraglyme electrolyte inhibits the activity of water molecules and thus avoids the formation of byproduct Zn_(4)ClO_(4)(OH)7·Meanwhile,highly stable Zn plating/stripping for over 1500 h,an average coulombic efficiency of>99%in long-term cycling,and ultralong storage life(the cells can work well after stored over 1 year)are simultaneously realized in the novel electrolyte.Benefitting from these aspects,the Zn-MnO_(2)batteries manifest high specific capacity of 132 mA h g^(-1),an operating voltage of 1.25 V,and a capacity retention of>98%after 1000 cycles at a current density of 200 mA g^(-1).

Intrinsic lithiophilic carbon host derived from bacterial cellulose nanofiber for dendrite-free and long-life lithium metal anode

Although lithium metal is considered a promising anode for advanced Li-S and Li-air batteries,the uncontrolled dendrite growth and infinite volume change impede its practical application.Herein,we report an ideal framework composed of carbonized bacterial cellulose(CBC)nanofibers,which shows intrinsic lithiophilicity to molten lithium without any lithiophilic surface modification.The wetting behavior of molten lithium can be significantly improved because its surface functional groups provide thermodynamical driving force,and the high surface roughness derived from nanocracks leads to rapid infusion in kinetics.The hybrid anode exhibits long cycle life up to 2000 h and excellent deep stripping-platting capacity up to 20 mAh·cm^(-2).When the anode is assembled with LiFePO_(4) cathode,the full cell delivers a good cycling stability up to 700 cycles.This is attributed to the intrinsic lithiophilic scaffold,which can not only lower the nucleation barrier of Li and provide uniform nucleation sites for stable Li stripping/plating,but also offer interspace to accommodate volume fluctuation of lithium during long cycling.This work provides a new manner to achieve a series of intrinsic lithiophilic carbon skeletons based on the large family of biomass materials and organic materials.

Analysis of All-Carbon Brick Bottom and Ceramic Cup Synthetic Hearth Bottom

One of the bottlenecks of the blast furnace （BF） campaign is the life length of hearth bottom. The basic reason for the erosion of hearth bottom is its direct contact with hot metal. According to the theory of heat transfer, models of BF hearth bottom are built based on the actual examples using software and VC language, and the calculated results are in good agreement with the data of BF dissection after blowing out. The temperature distribution and the capability of the resistance to erosion for different structures of hearth bottom are analyzed, especially the two prevalent kinds of hearth bottom arrangements called ＂the method of heat transfer＂ for all-carbon brick bottom and ＂the method of heat isolation＂ for ceramic synthetic hearth bottom. Features of the two kinds of hearth bottoms are analyzed. Also the different ways of protecting the hearth bottom are clarified, according to some actual examples. After that, the same essence of prolonging life, and the fact that the existence of a ＂protective skull＂ with low thermal conductivity between the hot metal and brick layers is of utmost importance are shown.

Nitrogen-doped carbon stabilized Li Fe0.5Mn0.5PO4/rGO cathode materials for high-power Li-ion batteries

Exploring high ion/electron conductive olivine-type transition metal phosphates is of vital significance to broaden their applicability in rapid-charging devices.Herein,we report an interface engineered Li Fe0.5Mn0.5PO4/rGO@C cathode material by the synergistic effects of r GO and polydopamine-derived N-doped carbon.The well-distributed Li Fe0.5Mn0.5PO4nanoparticles are tightly anchored on r GO nanosheet benefited by the coating of N-doped carbon layer.The design of such an architecture can effectively suppress the agglomeration of nanoparticles with a shortened Li+transfer path.Meantime,the high-speed conducting network has been constructed by r GO and N-doped carbon,which exhibits the face-to-face contact with Li Fe0.5Mn0.5PO4nanoparticles,guaranteeing the rapid electron transfer.These profits endow the Li Fe0.5Mn0.5PO4/rGO@C hybrids with a fast charge-discharge ability,e.g.a high reversible capacity of 105 m Ah·g^-1at 10 C,much higher than that of the Li Fe0.5Mn0.5PO4@C nanoparticles(46 mA·h·g^-1).Furthermore,a 90.8%capacity retention can be obtained even after cycling 500 times at 2 C.This work gives a new avenue to fabricate transition metal phosphate with superior electrochemical performance for high-power Li-ion batteries.

Flexible rechargeable Ni//Zn battery based on self-supported NiCo_2O_4 nanosheets with high power density and good cycling stability

The overall electrochemical performances of Ni-Zn batteries are still far from satisfactory, specifically for rate performance and cycling stability Herein, we demonstrated a high-performance flexible Ni//Zn battery with outstanding durability and high power density based on selfsupported NiCo_2 O_4 nanosheets as cathode and Zn nanosheets as anode. This Ni//Zn battery is able to deliver a remarkable capacity of183.1 mAh g^(-1) and a good cycling performance(82.7% capacity retention after 3500 cycles). More importantly, this battery achieves an admirable power density of 49.0 kW kg^(-1) and energy density of 303.8 Wh kg^(-1), substantially higher than most recently reported batteries. With such excellent electrochemical performance, this battery will have great potential as an ultrafast power source in practical application.

Nb_2O_5-carbon core-shell nanocomposite as anode material for lithium ion battery

Nb2O5-carbon nanocomposite is synthesized through a facile one-step hydrothermal reaction from sucrose as the carbon source, and stuclled as an anode material for high-performance lithium ion battery. The structural characterizations reveal that the nanocomposite possesses a core-shell structure with a thin layer of carbon shell homogeneously coated on the Nb2O5 nanocrystals. Such a unique structure enables the composite electrode with a long cycle life by preventing the Nb2O5 from volume change and pulverization during the charge-discharge process. In addition, the carbon shell efficiently improves the rate capability. Even at a current density of 500 mA.g-1, the composite electrode still exhibits a specific capacity of ~100 mAh.g-1. These results suggest the possibility to utilize the Nb2O5-carbon core-shell composite as a high performance anode material in the practical application of lithium ion battery.

Layered barium vanadate nanobelts for high-performance aqueous zinc-ion batteries

Aqueous zinc-ion batteries(ZIBs)are deemed as the idea option for large-scale energy storage systems owing to many alluring merits including low manufacture cost,environmental friendliness,and high operations safety.However,to develop high-performance cathode is still significant for practical application of ZIBs.Herein,Ba_(0.23)V_(2)O_(5)·1.1H_(2)O(BaVO)nanobelts were fabricated as cathode materials of ZIBs by a typical hydrothermal synthesis method.Benefiting from the increased interlayer distance of 1.31 nm by Ba2+ and H2O pre-intercalated,the obtained BaVO nanobelts showed an excellent initial discharge capacity of 378 mAh·g^(-1) at 0.1 A·g^(-1),a great rate performance(e.g.,172 mAh·g^(-1) at 5 A·g^(-1)),and a superior capacity retention(93% after 2000 cycles at 5 A·g^(-1)).

Defect-engineered Mn_(3)O_(4)/CNTs composites enhancing reaction kinetics for zinc-ions storage performance

The designing of reasonable nanocomposite materials and proper introduction of defect engineering are of great significance for the improvement of the poor electronic conductivity and slow reaction kinetics of manganese-based compounds. Herein, we report manganese-deficient Mn_(3)O_(4) nanoparticles which grow in-situ on highly conductive carbon nanotubes(CNTs)(denoted as DMOC) as an advanced cathode material for aqueous rechargeable zinc-ion batteries(RAZIBs). According to experimental and calculation results, the DMOC cathode integrates the advantages of enriched Mn defects and small particle size. These features not only enhance electronic conductivity but also create more active site and contribute to fast reaction kinetics. Moreover, the structure of DMOC is maintained during the charging and discharging process, thus benefiting for excellent cycle stability. As a result, the DMOC electrode delivers a high specific capacity of 420.6 m A h g^(-1) at 0.1 A g^(-1) and an excellent cycle life of 2800 cycles at 2.0 A g^(-1) with a high-capacity retention of 84.1%. In addition, the soft-packaged battery assembled with DMOC cathode exhibits long cycle life and high energy density of 146.3 Wh kg^(-1) at 1.0 A g^(-1) . The results are beneficial for the development of Zn/Mn_(3)O_(4) battery for practical energy storage.

Novel fusiform core-shell-MOF derived in tact metal@carb on composite:An efficient cathode catalyst for aqueous and solid-state Zn-air batteries

Owing to the varied mechanisms of ORR/OER,exploiting cost-effective bifunctional catalysts with robust ORR/OER activities and excellent performances in Zn-air batteries is still a challenge.In this work,the Co/CoO@NSC bifunctional catalyst is obtained by using Zn-MOF@Co-MOF as self-template.The Co/CoO@NSC composite has interconnected porous architecture with in tact metal@carb on structure,exhibiting superior electrocatalytic activities toward ORR and OER that can be comparable with the Pt/C and RuO_(2) catalysts,respectively.The Co/CoO@NSC-based aqueous Zn-air battery achieves a high specific capacity(759.7 mAh/g)and energy density(990.5 Wh/kg),and ultra-long rechargeable property(more than 400 h/1200 cycles).The Co/CoO@NSC-based solid-state Zn-air battery also delivers an excellent performance with a long cycle life(more than 143 h/858 cycles).Most importantly,the newly synthesized and recharged Co/CoO@NSC-based solid-state Zn-air battery can be used to light up a 2 V LED lamp for more than 28 h,demonstrating the superior practicability as rechargeable power source.

A General Self-Sacrifice Template Strategy to 3D Heteroatom-Doped Macroporous Carbon for High-Performance Potassium-Ion Hybrid Capacitors

Potassium-ion hybrid capacitors(PIHCs)tactfully combining capacitor-type cathode with battery-type anode have recently attracted increasing attentions due to their advantages of decent energy density,high power density,and low cost;the mismatches of capacity and kinetics between capacitor-type cathode and battery-type anode in PIHCs yet hinder their overall performance output.Herein,based on prediction of density functional theory calculations,we find Se/N co-doped porous carbon is a promising candidate for K+storage and thus develop a simple and universal self-sacrifice template method to fabricate Se and N co-doped three-dimensional(3D)macroporous carbon(Se/N-3DMpC),which features favorable properties of connective hier-archical pores,expanded interlayer structure,and rich activity site for boosting pseudocapacitive activity and kinetics toward K^(+)storage anode and enhancing capacitance performance for the reversible anion adsorption/desorption cath-ode.As expected,the as-assembled PIHCs full cell with a working voltage as high as 4.0 V delivers a high energy density of 186 Wh kg^(−1) and a power output of 8100 W kg^(−1) as well as excellent long service life.The proof-of-concept PIHCs with excellent performance open a new avenue for the development and application of high-performance hybrid capacitors.

Electrolyte design strategies towards long-term Zn metal anode for rechargeable batteries

Rechargeable Zinc(Zn)batteries exhibit great potentials as alternative energy storage devices due to their high safety,low cost,and environmental friendliness.However,the long-standing issues of low Coulombic efficiency(CE)and poor cycle stability of Zn anode,derived from dendrite,H_(2)evolution,and passivation are directly related to their thermodynamic instability in aqueous electrolyte,severely shorten the battery's cycle life.Recently reported electrolyte design strategies,which have made great progress to address Zn metal anode problems,are summarized into two categories,that is,aqueous electrolytes about cation-water interaction controlling and interface adjusting,and novel types of electrolytes towards less water,non-aqueous solvents,even no solvents.The final section shows the brief comparisons,including failure mechanisms of electrolyte exhaustion and short circuit for aqueous and nonaqueous electrolyte based full cells respectively,and possible perspectives for future research.

Carbon coated ultrasmall anatase TiO_2 nanocrystal anchored on N,S-RGO as high-performance anode for sodium ion batteries

Anatase TiO_2 has been investigated as one of the most promising anode materials for sodium ion batteries(SIBs)with low cost and high theoretical capacity.Herein,a composite material of TiO_2 /N,S-RGO@C with carbon coated ultrasmall anatase TiO_2 anchored on nitrogen and sulfur co-doped RGO matrix was successfully prepared by a rational designed process.The composite structure exhibited ultrasmall crystal size,rich porous structure,homogeneous heteroatoms doping and thin carbon coating,which synergistically resulted in elevated electron and ion transfer.The anode exhibited high rate capacities with good reversibility under high rate cycling.The carbon coating was investigated to be effective to prevent active material falling and lead to long term cycling performance with a high capacity retention of 181 m Ah g^(à1)after 2000cycles at 2 C.Kinetic studies were carried out and the results revealed that the superior performance of the composite material were derived from the decreased charge transfer resistance and elevated ion diffusion.Results suggested that the TiO_2 /N,S-RGO@C composite is a promising anode material for sodium ion batteries.

Functional lithiophilic polymer modified separator for dendrite-free and pulverization-free lithium metal batteries

Severe performance drop and fire risk due to the uneven lithium(Li) dendrite formation and growth during charge/discharge process has been considered as the major obstacle to the practical application of Li metal batteries.So inhibiting dendrite growth and producing a stable and robust solid electrolyte interface(SEI) layer are essential to enable the use of Li metal anodes.In this work,a functional lithiophilic polymer composed of chitosan(CTS),polyethylene oxide(PEO),and poly(triethylene glycol dimethacrylate)(PTEGDMA),was homogeneously deposited on a commercial Celgard separator by combining electrospraying and polymer photopolymerization techniques.The lithiophilic environment offered by the CTS-PEO-PTEGDMA layer enables uniform Li deposition and facilitates the formation of a robust homogeneous SEI layer,thus prevent the formation and growth of Li dendrites.As a result,both Li/Li symmetric cells and LiFePO4/Li full cells deliver significantly enhanced electrochemical performance and cycle life.Even after 1000 cycles,the specific capacity of the modified full cell could be maintained at65.8 mAh g^(-1), twice which of the unmodified cell(32.8 mAh g^(-1)).The long-term cycling stability in Li/Li symmetric cells,dendrite-free anodes in SEM images and XPS analysis suggest that the pulverization of the Li anode was effectively suppressed by the lithiophilic polymer layer.