In situ formed cross-linked polymer networks as dual-functional layers for high-stable lithium metal batteries

Lithium-metal anodes(LMAs)have been recognized as the ultimate anodes for next-generation batteries with high energy density,but stringent assembly-environment conditions derived from the poor moisture stability dramatically hinder the transformation of LMAs from laboratory to industry.Herein,an in situ formed cross-linked polymer layer on LMAs is designed and constructed by a facile thiol-acrylate click chemistry reaction between poly(ethylene glycol)diacrylate(PEGDA)and the crosslinker containing multi thiol groups under UV irradiation.Owing to the hydrophobic nature of the layer,the treated LMAs demonstrate remarkable humid stability for more than 3 h in ambient air(70%relative humidity).The coating humid-resistant protective layer also possesses a dual-functional characterization as solid polymer electrolytes by introducing lithium bis(trifluoromethanesulfonyl)imide in the system in advance.The intimate contact between the polymer layer and LMAs reduces interfacial resistance in the assembled Li/LiFePO_(4)or Li/LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)full cell effectively,and endows the cell with an outstanding cycle performance.

Fe, V-co-doped C_(2)N for electrocatalytic N_(2)-to-NH_(3) conversion

Designing providential catalyst is the key to drive the electrochemical nitrogen reduction reactions(NRR),which is referring to multiple intermediates and products. By means of density functional theory(DFT)calculations, we studied heteronuclear bi-atom electrocatalyst(HBEC) for NRR. Our results revealed that compared to homonuclear bi-atom electrocatalyst(Fe_2@C_2N, V_2@C_2N), Fe, V-co-doped C_2N(Fe V@C_2N)had a smaller limiting potential of-0.17 V and could accelerate N_2-to-NH_3 conversion through the enzymatic pathway of NRR. Importantly, N–N bond length monotonically increases with increasing the Bader charges of adsorbed N_2 molecule but decreases with increasing the Bader charge difference of two adsorbed N atoms. Additionally, the Fe V@C_2N could suppress the production of H_2 by the preferential adsorption and reduction of N_2 molecule. Thus, the as-designed HBEC may have the outstanding electrochemical NRR performance. This work opens a new perspective for NRR by HBECs under mild conditions.

A High-Capacity Ammonium Vanadate Cathode for Zinc-Ion Battery

Given the advantages of being abundant in resources,environmental benign and highly safe,rechargeable zinc-ion batteries(ZIBs)enter the global spotlight for their potential utilization in large-scale energy storage.Despite their preliminary success,zinc-ion storage that is able to deliver capacity>400 mAh g^-1 remains a great challenge.Here,we demonstrate the viability of NH4V4O10(NVO)as high-capacity cathode that breaks through the bottleneck of ZIBs in limited capacity.The first-principles calculations reveal that layered NVO is a good host to provide fast Zn^2+ions diffusion channel along its[010]direction in the interlayer space.On the other hand,to further enhance Zn^2+ion intercalation kinetics and long-term cycling stability,a three-dimensional(3D)flower-like architecture that is self-assembled by NVO nanobelts(3D-NVO)is rationally designed and fabricated through a microwave-assisted hydrothermal method.As a result,such 3D-NVO cathode possesses high capacity(485 mAh g^-1)and superior long-term cycling performance(3000 times)at 10 A g^-1(~50 s to full discharge/charge).Additionally,based on the excellent 3D-NVO cathode,a quasi-solid-state ZIB with capacity of 378 mAh g^-1is developed.

Rapid and reversible Na deposition onto Al nanosheet arrays

Sodium metal battery(SMB)is regarded as a promising candidate for next-generation high-energy battery due to high theoretical capacity and abundant natural resources.However,the growth of sodium dendrites and large volume expansion during the processes of sodium plating and stripping seriously restrict the practical application of SMBs.Here,a three-dimensional skeleton of aluminum nanosheet arrays(Al NSARs)is constructed by a facile etching approach to achieve rapid and reversible Na plating/stripping.The Al NSARs with large geometric specific surface and plentiful cavities can provide rich active nucleation sites,reduce local current density and accommodate Na volume change,which lead to uniform deposition of sodium with dendrite-free morphology.As a result,Na plating/stripping on Al NSARs can stably operate over 650 cycles at 2 mA cm^(-2)/2 mAh cm^(-2)with average Coulombic efficiency(CE)of 100.0%and low potential polarization of 27 mV.Moreover,the full cell of Na_(s)V_(2)(PO_(4))_(3)||Al NSARs@Na can run for over 1800 cycles at a high rate of 20C.These superior properties,combined with relatively low cost and weight of Al,enable our AlNSARs to begreat prospect for practical applications.

Co-doped graphene edge for enhanced N2-to-NH3 conversion

N2 fixation in atmosphere is an important issue in modern chemistry.Designing an ideal electrochemical nitrogen reduction reaction(NRR)catalyst to overcome the sluggish reaction kinetic and ultralow selectivity is still the significant challenge.Herein,we screened the potential catalyst to accelerate N2 fixation by designing the single transition metal(TM)atoms(Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn,Mo,W,Ru and Rh)supported on the edge of graphene.Our calculations revealed that the Co atom supported on the graphene edge could selectively stabilize*N2 H species and destabilize*NH2 species,leading to the highest catalytic activity and selectivity for N2 fixation at the ambient conditions.In addition,the enzymatic mechanism of eNNR have the lowest overpotential of 0.72 V.This theoretical work will give a new perspective to design an available catalyst for NRR.

Promoted CO2 electroreduction over indium-doped SnP3: A computational study

It is generally considered that the hydrogenation of CO2 is the critical bottleneck of the CO2 electroreduction.In this work,with the aid of density functional theory(DFT)calculations,the catalytic hydrogenation of CO2 molecules over Indium-doped SnP3 catalyst were systematically studied.Through doping with indium(In)atom,the energy barrier of CO2 protonation is reduced and OCHO*species could easily be generated.This is mainly due to the p orbital of In exhibits strong hybridization with the p orbital of O,indicating that there is a strong interaction between OCHO*and In-doped SnP3 catalyst.As a result,In-doped SnP3 possesses high-efficiency and high-selectivity for converting CO2 into HCOOH with a low limiting potential of-0.17 V.Our findings will offer theoretical guidance to CO2 electroreduction.

Carbon‐based materials for all‐solid‐state zinc–air batteries

Solid‐state Zn–air batteries(ZABs)hold great potential for application in wearable and flexible electronics.However,further commercialization of current ZABs is still limited by the poor stability and low energy efficiency.It is,thus,crucial to develop efficient catalysts as well as optimize the solid electrolyte system to unveil potential of the ZAB technology.Due to the low cost and versatility in tailoring the structures and properties,carbon materials have been extensively used as the conductive substrates,catalytic air electrodes,and important components in the electrolytes for the solid‐state ZABs.Within this context,we discuss the challenges facing current solid‐state ZABs and summarize the strategies developed to modify properties of carbon‐based electrodes and electrolytes.We highlight the metal−organic framework/covalent organic framework‐based electrodes,heteroatom‐doped carbon,and the composites formed of carbon with metal oxides/sulfides/phosphides.We also briefly discuss the progress of graphene oxide‐based solid electrolyte.

Gallium-based anodes for alkali metal ion batteries

Alkali metal ion batteries(AMIBs)are playing an irreplaceable part in the energy revolution,due to their intrinsic advantages of large capacity/power density and abundance of alkali metal ions in the earth’s crust.Despite their great promise,the inborn deficiencies of commercial graphite and other anodes being researched so far call for the quest of better alternatives that exhibit all-round performance with the balance of energy/power density and cycling stability.Gallium-based materials,with impressive capacity utilization and self-healing ability,provide an anticipated solution to this conundrum.In this review,an overview on the recent progress of gallium-based anodes and their storage mechanism is presented.The current strategies used as engineering solutions to meet the scientific challenges ahead are discussed,in addition to the insightful outlook for possible future study.

Self-Assembled VS4 Hierarchitectures with Enhanced Capacity and Stability for Sodium Storage

Sodium-ion batteries(SIBs)have become an auspicious candidate for largescale energy storage by cause of low cost,natural abundance,and similar working principle with lithium-ion batteries(LIBs).At present,there is an urgent need to explore superior anode materials with rapid and stable sodiation/desodiation.Herein,3D self-assembled VS4 curly nanosheets hierarchitectures(VS4-CN-Hs)are developed for SIB anodes,where VS4 possesses a large theoretical sodium storage capacity,and the building block of nanosheets has large exposed surface area to the electrolyte as well as the constructed hierarchitectures can provide abundant buffer space to alleviate the volume expansion.As a result,VS4-CN-Hs anode possesses excellent electrochemical performance under a wide voltage window of 0.01–3.0 V,such as high reversible capacity of 863 mA h g^(−1) at 0.1 A g^(−1),marvelous rate feature(444 mA h g^(−1) at 10 A g^(−1)),and extralong cycle stability(386 mA h g^(−1) after 1000 times at 5 A g^(−1)).

High-performance flexible nanocomposites with superior fire safety and ultra-efficient electromagnetic interference shielding

High-performance multifunctional polymeric materials integrated with high fire safety,excel-lent mechanical performances and electromagnetic interference(EMI)shielding properties have great prospects in practical applications.However,designing highly fire-safe and mechanically ro-bust EMI shielding nanocomposites remains a great challenge.Herein,hierarchical thermoplastic polyurethane/cyclophosphazene functionalized titanium carbide/carbon fiber fabric(TPU/CP-Ti_(3)C_(2)T_(x)/CF)nanocomposites with high fire safety and mechanical strength and toughness were prepared through the methods of melt blending,layer-by-layer stacking and thermocompression.The TPU/CP-Ti_(3)C_(2)T_(x)showed improved thermal stability.Moreover,the peak of heat release rate and total heat release of the hi-erarchical TPU sample containing 4.0 wt.%CP-Ti_(3)C_(2)T_(x)were respectively reduced by 64.4%and 31.8%relative to those of pure TPU,which were far higher than those of other TPU-based nanocomposites.The averaged EMI shielding effectiveness value of the hierarchical TPU/CP-Ti_(3)C_(2)T_(x)-2.0/CF nanocomposite reached 30.0 dB,which could satisfy the requirement for commercial applications.Furthermore,the ten-sile strength of TPU/CP-Ti_(3)C_(2)T_(x)-2.0/CF achieved 43.2 MPa,and the ductility and toughness increased by 28.4%and 84.3%respectively compared to those of TPU/CF.Interfacial hydrogen bonding in combination with catalytic carbonization of CP-Ti_(3)C_(2)T_(x)nanosheets and continuous conductive network of CF were re-sponsible for the superior fire safety,excellent EMI shielding and outstanding mechanical performances.This work offers a promising strategy to prepare multifunctional TPU-based nanocomposites,which have the potential for large-scale application in the fields of electronics,electrical equipment and 5 G facilities.

电解液添加剂多因子设计原则:以金属锂电池电解液添加剂全氟烷基磺酸钾盐为例

随着便携式电子设备、电动汽车、智能电网等领域的快速发展,市场对于高能量密度储能器件的需要日益增长.以石墨为负极的传统锂离子电池能量密度有限,尤其是与电动汽车动力电池的发展目标(300~500 Wh kg-1)尚有较大差距.因此,研究开发新一代电池技术十分迫切[1].

Electrolytes enriched by potassium perfluorinated sulfonates for lithium metal batteries

Lithium(Li) metal is widely considered as a promising anode for next-generation lithium metal batteries(LMBs) due to its high theoretical capacity and lowest electrochemical potential. However, the uncontrollable formation of Li dendrites has prevented its practical application. Herein, we propose a kind of multifunctional electrolyte additives(potassium perfluorinated sulfonates) from the multi-factor principle for electrolyte additive molecular design(EDMD) view to suppress the Li dendrite growth. The effects of these additives are revealed through experimental results, molecular dynamics simulations and firstprinciples calculations. Firstly, K^(+)can form an electrostatic shield on the surface of Li anode to prevent the growth of Li dendrites. Secondly, potassium perfluorinated sulfonates can improve the activity of electrolytes as co-conductive salts, and lower the electro-potential of Li nucleation. Thirdly, perfluorinated sulfonate anions not only can change the Li^(+)solvation sheath structure to decrease the desolvation energy barrier and increase the ion migration rate, but also can be partly decomposed to form the superior solid electrolyte interphase(SEI). Benefited from the synergistic effects, an outstanding cycle life over250 h at 1 m A cm^(-2) is achieved in symmetric Li||Li cells. In particular, potassium perfluorinated sulfonate additives(e.g., potassium perfluorohexyl sulfonate, denoted as K+PFHS) can also contribute to the formation of high-quality cathode electrolyte interphase(CEI). As a result, Li||LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2) full cells exhibit significantly enhanced cycling stability. This multi-factor principle for EDMD offers a unique insight on understanding the electrochemical behavior of ion-type electrolyte additives on both the Li metal anode and high-voltage cathode.

Transition metal carbides in electrocatalytic oxygen evolution reaction

Oxygen evolution reaction(OER) is admitted to an important half reaction in water splitting for sustainable hydrogen production.The sluggish four-electron process is known to be the bottleneck for enhancing the efficiency of OER.In this regard,tremendous efforts have been devoted to developing effective catalysts for OER.In addition to Ir-or Ru-based oxides taken as the benchmark,transition metal carbides have attracted ever-increasing interest due to the high activity and stability as low-cost OER electrocatalysts.In this review,the transition metal carbides for water oxidation electrocatalysis concerning design strategies and synthesis are briefly summarized.Some typical applications for various carbides are also highlighted.Besides,the development trends and outlook are also discussed.

Oxyvanite V3O5:A new intercalation-type anode for lithium-ion battery

In the present study,V3O5 microcrystals that synthesized via vacuum calcination are employed as anodes for lithium-ion batteries(LIBs)for the first time.Despite the widely observed sluggish reaction kinetics and poor cycling stability in most microsized transition metal oxides,the V3O5 microcrystals exhibit excellent rate capability(specific capacities of 144 and 125 mAh g^−1 are achieved at extremely high current densities of 20 and 50 A g^−1,respectively)and long-term cycling performance(specific capacity of 117 mAh g^−1 is sustained over 2000 cycles at 50 A g^−1).It is ascribed to the three-dimensional open-framework structure of the V3O5 microcrystals as a major factor in dictating the fast reaction kinetics(lithium diffusion coefficient:~10−9 cm^2 s^−1).In addition,significant insight into the reaction mechanism of the V3O5 microcrystals in concomitant its phase evolution are obtained from ex-situ XRD study,revealing that the V3O5 microcrystals undergo intercalation reaction with insignificant structural change in response to lithiation/delithiation.

A double crosslinking MXene/cellulose nanofiber layered film for improving mechanical properties and stable electromagnetic interference shielding performance

With the discovery of the two-dimensional(2D) MXene, it shows a great application potential in the field of electromagnetic interference(EMI) shielding, but the mechanical brittleness and easy oxidation of MXene limit its wide application. For this reason, a double crosslinking strategy is provided to solve the above problems in a nacre-like “brick-mortar” layered MXene/cellulose nanofiber(MXene/CNF) film.Typically, the film was firstly suffered by dopamine modification, then was further reinforced by secondary Ca^(2+)bridging, so as to obtain excellent mechanical properties and antioxidative EMI shielding performance. Comparing with the single crosslinking, the double crosslinking strategy reveals a higher efficiency in improving the mechanical property. The mechanical strength and toughness of the double crosslinking MXene/CNF film can increase to 142.2 MPa and 9.48 MJ/m^(3), respectively. More importantly, while achieving good mechanical properties, the MXene composite film still holds a very stable EMI shielding performance of more than 44.6 dB when suffering from the oxidation treatment of hightemperature annealing, showing excellent anti-oxidation ability and environment tolerance. Therefore,this work provides a universal but effective double crosslinking strategy to solve the mechanical brittleness and easy oxidation of MXene-based composites, thus showing a huge potential in flexible EMI shielding applications.

Electrospun Sb2Se3@C nanofibers with excellent lithium storage properties

Antimony-based materials have become promising anodes within lithium-ion batteries(LIBs)due to their low cost and the high theoretical capacity.However,there is a potential to further enhance the electrochemical performance of such antimony-based materials.Herein,Sb2Se3@C nanofibers(Sb2Se3@CNFs)are designed and obtained via a novel electrospinning method.Upon electrochemically testing as an anode within LIBs,the Sb2Se3@CNFs(annealed at 600℃)delivers a remarkably good cycling performance of 625 mAh/g at 100 mA/g after 100 cycles.Moreover,it still remains at 490 mAh/g after 500 cycles with an applied current density of 1.0 A/g.The excellent performance of the Sb2 Se3@CNFs can be attributed to the fact that the N-doped C matrices not only remit the volume expansion of materials,but also enhance the electrical and ionic conductivity thusly increasing the lithium-ion diffusion.The obtained Sb2Se3@CNFs are promising anode for LIBs in the future.

Robust double-layered ANF/MXene-PEDOT:PSS Janus films with excellent multi-source driven heating and electromagnetic interference shielding properties

The strategy of incorporating polymers into MXene-based functional materials has been widely used to improve their mechanical properties,however with inevitable sacrifice of their electrical conductivity and electromagnetic interference(EMI)shielding performance.This study demonstrates a facile yet efficient layering structure design to prepare the highly robust and conductive double-layer Janus films comprised of independent aramid nanofiber(ANF)and Ti3C2Tx MXene/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)layers.The ANF layer serves to provide good mechanical stability,whilst the MXene/PEDOT:PSS layer ensures excellent electrical conductivity.Doping PEDOT:PSS into the MXene layer enhances the interfacial bonding strength between the MXene and ANF layers and improves the hydrophobicity and water/oxidation resistance of MXene layer.The resultant ANF/MXene-PEDOT:PSS Janus film with a conductive layer thickness of 4.4μm was shown to display low sheet resistance(2.18Ω/sq),good EMI shielding effectiveness(EMI SE of 48.1 dB),high mechanical strength(155.9 MPa),and overall toughness(19.4 MJ/m^(3)).Moreover,the excellent electrical conductivity and light absorption capacity of the MXene-PEDOT:PSS conductive layer mean that these Janus films display multi-source driven heating functions,producing excellent Joule heating(382℃ at 4 V)and photothermal conversion(59.6℃ at 100 mW/m^(2))properties.

Multi-hierarchical flexible composites towards superior fire safety and electromagnetic interference shielding

Vast amounts of electromagnetic waves are generated in modern society,which severely endanger human health and cause instrument disturbance.Furthermore,practical application of electromagnetic shielding polymer-based materials aspires to flame retardancy.Herein,cellulose acetate butyrate modified ammonium polyphosphate(CAPP)and phosphoramide flame retardant decorated short carbon fiber(MSCF)were synthesized separately and then simultaneously blended into thermoplastic polyurethane(TPU)to prepare a series of flame retardant TPU composites.Then,the multi-hierarchical flexible TPU/CAPP/MSCF composites were fabricated via our self-developed air-assisted thermocompression method.The results revealed that the TPU/CAPP/MSCF showed improved thermal stability.Moreover,the TPU/10CA/2.5F incorporated with 10.0 wt.%CAPP and 2.5 wt.%MSCF respectively exhibited 77.8%and 58.6%reduction in peak of heat release rate(PHRR)and total heat release(THR),compared to those of pure TPU.In addition,the TPU/10CA/2.5F passed the UL-94 V-0 rating test and achieved a higher limit oxygen index(LOI)(27.3%)than pure TPU(21.7%).In the case of electromagnetic interference shielding effectiveness(EMI SE),the TPU/10CA/10.0F-SW with 10 wt.%CAPP and 10 wt.%MSCF dispersed in the surface layer and Ti_(3)C_(2)Tx MXene intercalated in the interlayer exhibited EMI SE of 43.8 dB in X band and 32.0 dB in K band.Summarily,synergistic effect between CAPP and MSCF together with scattered and multiply adsorbed effect of MSCF,MXene and CAPP was responsible for fire safety and EMI shielding property improvements.This work provides a fascinating strategy for fabricating multi-hierarchical flexible TPU composites with outstanding flame retardant and EMI shielding performances.

2-(Trifluoroacetyl) thiophene as an electrolyte additive for high-voltage lithium-ion batteries using LiCoO_(2) cathode

The development of high voltage electrolytes plays a critical role to achieve advanced lithium ion batteries with high energy density.Application of suitable electrolyte additives is a facile and effective way to achieve enhanced electrochemical perfo rmance at high voltage operation.In this work,2-(tri fluoroacetyl)thiophene(TFPN) was investigated as a functional electrolyte additive for high performance lithium ion batteries using high-voltage LiCoO2 cathode.When cycled between 3.0 V and 4.4 V at 0.5 C,the capacity retention of the LiCoO2 cathode significantly increases from 33.2 %-90.6 % by the addition of 0.5 wt%TFPN into the baseline electrolyte.Based on the measurements on impedance spectra and X-ray photoelectron spectra,the improved cycling performance is attributed to the preferential oxidation of TFPN on the cathode surface and thus form a protective layer to suppress the decomposition of both electrolyte solvent and lithium salt.This work presents that TFPN has great potential as functional additive for the development of high-voltage and high-energy-density lithium ion batteries.

Advances in metal phosphides for sodium-ion batteries

Sodium-ion batteries(SIBs)have been extensively studied as the potential alter-native to lithium-ion batteries(LIBs)due to the abundant natural reserves and low price of sodium resources.Nevertheless,Na+ions possess a larger radius than Li+,resulting in slow diffusion dynamics in electrode materials,and thus seeking appropriate anode materials to meet high performance standards has become a trend in the field of SIBs.In this context,owing to the advantages of high theoretical capacity and proper redox potential,metal phosphides(MPs)are considered to be the promising materials to make up for the gap of SIBs anode materials.In this review,the recent development of MPs anode materials for SIBs is reviewed and analyzed comprehensively and deeply,including the synthesis method,advanced modification strategy,electrochemical performance,and Na storage mechanism.In addition,to promote the wide application of the emerg-ing MPs anodes for SIBs,several research emphases in the future are pointed out to overcome challenges toward the commercial application.