Sandwich-type composited solid polymer electrolytes to strengthen the interfacial ionic transportation and bulk conductivity for all-solid-state lithium batteries from room temperature to 120℃

The insurmountable charge transfer impedance at the Li metal/solid polymer electrolytes(SPEs)interface at room temperature as well as the ascending risk of short circuits at the operating temperature higher than the melting point,dominantly limits their applications in solid-state batteries(SSBs).Although the inorganic filler such as CeO_(2)nanoparticle content of composite solid polymer electrolytes(CSPEs)can significantly reduce the enormous charge transfer impedance at the Li metal/SPEs interface,we found that the required content of CeO_(2)nanoparticles in SPEs varies for achieving a decent interfacial charge transfer impedance and the bulk ionic conductivity in CSPEs.In this regard,a sandwich-type composited solid polymer electrolyte with a 10%CeO_(2)CSPEs interlayer sandwiched between two 50%CeO_(2)CSPEs thin layers(sandwiched CSPEs)is constructed to simultaneously achieve low charge transfer impedance and superior ionic conductivity at 30℃.The sandwiched CSPEs allow for stable cycling of Li plating and stripping for 1000 h with 129 mV polarized voltage at 0.1 mA cm^(-2)and 30℃.In addition,the LiFePO_(4)/Sandwiched CSPEs/Li cell also exhibits exceptional cycle performance at 30℃and even elevated120℃without short circuits.Constructing multi-layered CSPEs with optimized contents of the inorganic fillers can be an efficient method for developing all solid-state PEO-based batteries with high performance at a wide range of temperatures.

A review of ^(17)O isotopic labeling techniques for solid-state NMR structural studies of metal oxides in lithium-ion batteries

Recent advances in utilizing ^(17)O isotopic labeling methods for solid-state nuclear magnetic resonance(NMR)investigations of metal oxides for lithium-ion batteries have yielded extensive insights into their structural and dynamic details.Herein,we commence with a brief introduction to recent research on lithium-ion battery oxide materials studied using ^(17)O solid-state NMR spectroscopy.Then we delve into a review of ^(17)O isotopic labeling methods for tagging oxygen sites in both the bulk and surfaces of metal oxides.At last,the unresolved problems and the future research directions for advancing the ^(17)O labeling technique are discussed.

Mitigating kinetic hindrance of single-crystal Ni-rich cathodes through morphology modulation,nickel reduction,and lithium vacancy generation achieved by terbium doping

Single crystallization has proven to be effective in enhancing the capacity and stability of Ni-rich LiNi_(1-x-y)Co_(x)Mn_(y)O_(2)(SNCM)cathode materials,particularly at high cut-off voltages.Nevertheless,the synthesis of high-quality single-crystal particles remains challenging because of severe particle agglomeration and irregular morphologies.Moreover,the limited kinetics of solid-phase Li^(+)diffusion pose a significant concern because of the extended diffusion path in large single-crystal particles.To address these challenges,we developed a Tb-doped single-crystal LiNi_(0.83)Co_(0.11)Mn_(0.06)O_(2)(SNCM-Tb)cathode material using a straightforward mixed molten salt sintering process.The Tb-doped Ni-rich single crystals presented a quasi-spherical morphology,which is markedly different from those reported in previous studies.Tb^(4+)oping significantly enhanced the dynamic transport of Li^(+)ions in the layered oxide phase by reducing the Ni valence state and creating Li vacancies.A SNCM-Tb material with 1 at%Tb doping shows a Li^(+)diffusion coefficient up to more than 9 times higher than pristine SNCM in the non-diluted state.In situ X-ray diffraction analysis demonstrated a significantly facilitated H1-H2-H3 phase transition in the SNCM-Tb materials,thereby enhancing their rate capacity and structural stability.SNCM-Tb exhibited a reversible capacity of 186.9 mA h g^(-1)at 5 C,retaining 94.6%capacity after 100 cycles at 0.5 C under a 4,5 V cut-off.Our study elucidates the Tb^(4+)doping mechanisms and proposes a scalable method for enhancing the performance of single-crystal Ni-rich NCM materials.

Metal-free two-dimensional phosphorene-based electrocatalyst with covalent P-N heterointerfacial reconstruction for electrolyte-lean lithium-sulfur batteries

The use of lithium-sulfur batteries under high sulfur loading and low electrolyte concentrations is severely restricted by the detrimental shuttling behavior of polysulfides and the sluggish kinetics in redox processes.Two-dimensional(2D)few layered black phosphorus with fully exposed atoms and high sulfur affinity can be potential lithium-sulfur battery electrocatalysts,which,however,have limitations of restricted catalytic activity and poor electrochemical/chemical stability.To resolve these issues,we developed a multifunctional metal-free catalyst by covalently bonding few layered black phosphorus nanosheets with nitrogen-doped carbon-coated multiwalled carbon nanotubes(denoted c-FBP-NC).The experimental characterizations and theoretical calculations show that the formed polarized P-N covalent bonds in c-FBP-NC can efficiently regulate electron transfer from NC to FBP and significantly promote the capture and catalysis of lithium polysulfides,thus alleviating the shuttle effect.Meanwhile,the robust 1D-2D interwoven structure with large surface area and high porosity allows strong physical confinement and fast mass transfer.Impressively,with c-FBP-NC as the sulfur host,the battery shows a high areal capacity of 7.69 mAh cm^(−2) under high sulfur loading of 8.74 mg cm^(−2) and a low electrolyte/sulfur ratio of 5.7μL mg^(−1).Moreover,the assembled pouch cell with sulfur loading of 4 mg cm^(−2) and an electrolyte/sulfur ratio of 3.5μL mg^(−1) shows good rate capability and outstanding cyclability.This work proposes an interfacial and electronic structure engineering strategy for fast and durable sulfur electrochemistry,demonstrating great potential in lithium-sulfur batteries.

Temperature inversion enables superior stability for low-temperature Zn-ion batteries

It is challenging for aqueous Zn-ion batteries(ZIBs)to achieve comparable low-temperature(low-T)performance due to the easy-frozen electrolyte and severe Zn dendrites.Herein,an aqueous electrolyte with a low freezing point and high ionic conductivity is proposed.Combined with molecular dynamics simulation and multi-scale interface analysis(time of flight secondary ion mass spectrometry threedimensional mapping and in-situ electrochemical impedance spectroscopy method),the temperature independence of the V_(2)O_(5)cathode and Zn anode is observed to be opposite.Surprisingly,dominated by the solvent structure of the designed electrolyte at low temperatures,vanadium dissolution/shuttle is significantly inhibited,and the zinc dendrites caused by this electrochemical crosstalk are greatly relieved,thus showing an abnormal temperature inversion effect.Through the disclosure and improvement of the above phenomena,the designed Zn||V_(2)O_(5)full cell delivers superior low-T performance,maintaining almost 99%capacity retention after 9500 cycles(working more than 2500 h)at-20°C.This work proposes a kind of electrolyte suitable for low-T ZIBs and reveals the inverse temperature dependence of the Zn anode,which might offer a novel perspective for the investigation of low-T aqueous battery systems.

Engineering a flexible and mechanically strong composite electrolyte for solid-state lithium batteries

Lithium-ion batteries(LIBs)have greatly facilitated our daily lives since 1990s[1,2].To meet the ever-increasing demand on energy density,Li metal is seen as the ultimate anode because of its ultra-high specific capacity(3860 m Ah/g)and the lowest electrochemical potential(-3.04 V vs.the standard hydrogen electrode)[3–6].However,issues of Li metal anode,such as Li dendrite formation and large volume change during plating/stripping。

Enabling high-efficiency ethanol oxidation on NiFe-LDH via deprotonation promotion and absorption inhibition

Nucleophile oxidation reaction(NOR), represented by ethanol oxidation reaction(EOR), is a promising pathway to replace oxygen evolution reaction(OER). EOR can effectively reduce the driving voltage of hydrogen production in direct water splitting. In this work, large current and high efficiency of EOR on a Ni, Fe layered double hydroxide(NiFe-LDH) catalyst were simultaneously achieved by a facile fluorination strategy. F in NiFe-LDH can reduce the activation energy of the dehydrogenation reaction, thus promoting the deprotonation process of NiFe-LDH to achieve a lower EOR onset potential. It also weakens the absorption of OH-and nucleophile electrooxidation products on the surface of NiFe-LDH at a higher potential, achieving a high current density and EOR selectivity, according to density functional theory calculations. Based on our experiment results, the optimized fluorinated NiFe-LDH catalyst achieves a low potential of 1.386 V to deliver a 10 mA cm^(-2)EOR. Moreover, the Faraday efficiency is greater than 95%, with a current density ranging from 10 to 250 mA cm^(-2). This work provides a promising pathway for an efficient and cost-effective NOR catalyst design for economic hydrogen production.

Hierarchically mesoporous carbon spheres coated with a single atomic Fe-N-C layer for balancing activity and mass transfer in fuel cells

Novel cost-effective fuel cells have become more attractive due to the demands for rare and expensive platinum-group metal(PGM)catalysts for mitigating the sluggish kinetics of the oxygen reduction reaction(ORR).The high-cost PGM catalyst in fuel cells can be replaced by earth-abundant transition-metalbased catalysts,that is,an Fe-N-C catalyst,which is considered one of the most promising alternatives.However,the performance of the Fe-N-C catalyst is hindered by the low catalytic activity and poor stability,which is caused by insufficient active sites and the lack of optimization of the triple-phase interface for mass transportation.Herein,a novel Fe–N–C catalyst consisting of mono-dispersed hierarchically mesoporous carbon sphere cores and single Fe atom-dispersed functional shells are presented.The synergistic effect between highly dispersed Fe-active sites and well-organized porous structures yields the combination of high ORR activity and high mass transfer performance.The half-wave potential of the catalyst in 0.1M H_(2)SO_(4) is 0.82 V versus reversible hydrogen electrode,and the peak power density is 812 mW·cm^(−2) in H_(2)–O_(2) fuel cells.Furthermore,it shows superior methanol tolerance,which is almost immune to methanol poisoning and generates up to 162 mW·cm^(−2) power density in direct methanol fuel cells.

A Universal Strategy For N-Doped 2D Carbon Nanosheets With Sub-Nanometer Micropore For High-Performance Supercapacitor

Preparing carbon nanosheets with precise control of open porous morphology via universal process and understanding the relationship between structure and capacitive performance are very urgent for achieving advanced supercapacitors.Herein,we propose a simple yet effective additive-free method to transform a bulk layered potassium phthalimide salt to novel nitrogen-doped twodimensional carbon sheets by self-activation during calcination.The obtained samples showed large-sized and flat structure with lateral size around 10μm,uniform sub-nanometer micropore size distribution of about 0.65 nm dimension,large specific surface area up to 2276.7 m^(2)g^(-1),and suitable nitrogen doping.Benefited from these merits,the optimized sample delivers a high specific capacitance of 345 F g^(-1)at 1 A g^(-1)and retains 270 F g^(-1)even at 50 A g^(-1)in6.0 M KOH electrolyte.Remarkably,the symmetric supercapacitor shows maximum energy densities of 16.43 Wh kg^(-1)and 23.6 Wh kg^(-1)in 6.0 M KOH and 1.0 M Na_(2)SO_(4)electrolytes,respectively.Importantly,on account the universality and simplicity of this method,the undoped as-prepared carbon sheet with uniform sub-nanometer micropore distribution can be synthesized from different potassium-containing salts with layered structure,which can be employed as a model for a deep understanding the effect of sub-nanometer micropores on capacitive performances.We find the number of micropores centered at 0.65 nm can be applied as one indicator to clarify the correlation between capacitance and critical pore size below 1 nm.

Promoting reaction kinetics of lithium polysulfides by cobalt polyphthalocyanine derived ultrafine Co nanoparticles mono-dispersed on graphene flakes for Li-S batteries

Lithium-sulfur(Li-S)batteries have been considered as the next generation high energy storage devices.However,its commercialization has been hindered by several issues,especially the dissolution and shuttle of the soluble lithium polysulfides(LiPSs)as well as the slow reaction kinetics of LiPSs which may make shuttling effect even worse.Herein,we report a strategy to address this issue by in-situ transformation of Co−N_(x) coordinations in cobalt polyphthalocyanine(CoPPc)into Co nanoparticles(Co NPs)embedded in carbon matrix and mono-dispersed on graphene flakes.The Co NPs can provide rich binding and catalytic sites,while graphene flakes act as ideally LiPSs transportation and electron conducting platform.With a remarkable enhanced reaction kinetics of LiPSs via these merits,the sulfur host with a sulfur content up to 70 wt%shows a high initial capacity of 1048 mA∙h/g at 0.2C,good rate capability up to 399 mA·h/g at 2C.

Tailoring the Porous Structure of Mono-dispersed Hierarchically Nitrogen-doped Carbon Spheres for Highly Efficient Oxygen Reduction Reaction

The search for a low-cost metal-free cathode material with excellent mass transfer structure and catalytic activity in oxygen reduction reaction(ORR)is one of the most challenging issues in fuel cells.In this work,nitrogen-rich mphenylenediamine is introduced into the synthesis of porous carbon spheres to tune the pore structure and nitrogen-doped active sites.As a result,more pyridinic N and pyrrolic N functional species were observed at the interior and surface of the carbon spheres.The introduction of m-phenylenediamine also regulated the nucleating of precursors,an urchin-like mesoporous surface structure ensures point contact and less agglomeration between each particle was obtained.With optimized proportion of micropores/mesopores and improved nitrogen-contained functional species,the ORR activity can be remarkably improved.The half-wave potential of this catalyst could achieve to 0.81 V(versus RHE)which is only 42 m V lower than commercial Pt/C catalyst.Furthermore,the optimized cathode catalyst achieved a 69 m W cm-2 maximum power density when operated in direct methanol fuel cells at room temperature.

Lithium-site substituted argyrodite-type Li_(6)PS_(5)I solid electrolytes with enhanced ionic conduction for all-solid-state batteries

Argyrodites,Li_(6)PS_(5)X(X=Cl,Br,I),have piqued the interest of researchers by offering promising lithium ionic conductivity for their application in all-solid-state batteries(ASSBs).However,other than Li_(6)PS_(5)Cl(651Cl)and Li_(6)PS_(5)Br(651Br),Li_(6)PS_(5)I(651I)shows poor ionic conductivity(10^(-7)S cm^(-1)at 298 K).Herein,we present Al-doped 651I with I^(-)/S^(2-)site disordering to lower activation energy(Ea)and improve ionic conductivity.They formed argyrodite-type solid solutions with a composition of(Li_(6–3x)Al_(x))PS_(5)I in 0≤x≤0.10,and structural analysis revealed that Al^(3+)is located at Li sites.Also,the Al-doped samples contained anion I^(-)/S^(2-)site disorders in the crystal structures and smaller lattice parameters than the non-doped samples.Impedance spectroscopy measurements indicated that Al-doping reduced the ionic diffusion barrier,Ea,and increased the ionic conductivity to 10^(-5)S cm^(-1);the(Li5.7Al0.1)PS5I had the highest ionic conductivity in the studied system,at 2.6×10^(-5)S cm^(-1).In a lab-scale ASSB,with(Li_(5.7)Al_(0.1))PS_(5)I functioned as a solid electrolyte,demonstrating the characteristics of a pure ionic conductor with negligible electronic conductivity.The evaluated ionic conduction is due to decreased Li+content and I^(-)/S^(2-)disorder formation.Li-site cation doping enables an in-depth understanding of the structure and provides an additional approach to designing betterperforming SEs in the argyrodite system.

Dynamically lithium-compensated polymer artificial SEI to assist highly stable lithium-rich manganese-based anode-free lithium metal batteries

Owing to the unique structure,anode-free lithium metal batteries(AFLMBs)have higher energy density and lower production cost than traditional lithium metal batteries(LMBs)or lithium-ion batteries(LIBs),However,AFLMBs suffer from an inherently finite Li reservoir and exhibit poor cycle stability,low Coulombic efficiency(CE)and severe dendrite growth.In this work,polydiallyl lithium disulfide(PDS-Li)was successfully synthesized and coated on Cu current collector by electrochemical polymerization.The PDS-Li acts as an additional lithium resource to compensate for the irreversible loss of lithium during cycling.In addition,the special structure and lithiophilicity of PDS-Li contribute to lower nucleation overpotential and uniform lithium deposition.When coupled with Li-rich manganese-based(LRM)cathode of Li1.2Mn0.54Ni0.13Co0.13O2,the anode-free full cell exhibits significantly improved cycle stability over 100 cycles and capacity retention of 63.3%and 57%after 80 and 100 cycles,respectively.We believe that PDS-Li can be used to ensure stable cycling performance and high-energy-density in AFLMBs.

Recent advances and practical challenges of high-energy-density flexible lithium-ion batteries

With the rapid iteration and update of wearable flexible devices,high-energy-density flexible lithium-ion batteries are rapidly thriving.Flexibility,energy density,and safety are all important indicators for flexible lithium-ion batteries,which can be determined jointly by material selection and structural design.Here,recent progress on high-energy-density electrode materials and flexible structure designs are discussed.Commercialized electrode materials and the next-generation high-energy-density electrode materials are analyzed in detail.The electrolytes with high safety and excellent flexibility are classified and discussed.The strategies to increase the mass loading of active materials on the electrodes by designing the current collector and electrode structure are discussed with keys of representative works.And the novel configuration structures to enhance the flexibility of batteries are displayed.In the end,it is pointed out that it is necessary to quantify the comprehensive performance of flexible lithium-ion batteries and simultaneously enhance the energy density,flexibility,and safety of batteries for the development of the next-generation high-energy-density flexible lithium-ion batteries.

MOF-derived 1D CGO Cathode for Efficient Solid Oxide Electrolysis Cells

Solid oxide electrolysis cells(SOECs)provide a promising way for converting renewable energy into chemical fuels.Traditionally,NiO/CGO(nickel-gadolinium doped ceria)cermet has shown its excellent properties in ionic and electronic conductivity under reducing conditions.Herein,we developed a novel 1D NiO/CGO cathode through a cerium metal-organic framework(MOF)derived process.The cathode’s 1D nanostructure integrated with a microchannel scaffold facilitates enhanced mass transport,providing vertically aligned pathways for CO_(2)and H_(2)O diffusion.Additionally,the 1D framework increases the number of interfacial sites and reduces ion diffusion distances,thereby simplifying electron/ion transport.Consequently,this advanced cathode achieved a significant breakthrough in SOEC performance,maintaining efficient CO_(2)and H_(2)O electrolysis at an extraordinary current density of 1.41 A/cm^(2)at 1.5 V and excellent stability over 24 h at 850℃.The enhanced performance of this newly developed cathode not only achieves a remarkable 100%improvement compared to those of NiO/CGO cathodes with varying geometrical configurations but also surpasses those of commercial NiO/CGO catalysts by an outstanding 40%when tested under identical conditions.The development of the 1D NiO/CGO enhances the efficiency and durability of ceramic cathodes for CO_(2)and H_(2)O co-electrolysis in SOECs and improves the scalability and effectiveness of SOECs in renewable energy applications.

Research progress in failure mechanisms and electrolyte modification of high-voltage nickel-rich layered oxide-based lithium metal batteries

High-voltage nickel(Ni)-rich layered oxide-based lithium metal batteries(LMBs)exhibit a great potential in advanced batteries due to the ultra-high energy density.However,it is still necessary to deal with the challenges in poor cyclic and thermal stability before realizing practical application where cycling life is considered.Among many improved strategies,mechanical and chemical stability for the electrode electrolyte interface plays a key role in addressing these challenges.Therefore,extensive effort has been made to address the challenges of electrode-electrolyte interface.In this progress,the failure mechanism of Ni-rich cathode,lithium metal anode and electrolytes are reviewed,and the latest breakthrough in stabilizing electrode-electrolyte interface is also summarized.Finally,the challenges and future research directions of Ni-rich LMBs are put forward.

World’s first spaceflight on-orbit demonstration of a flexible solar array system based on shape memory polymer composites

With a 10%reversible compressive strain in more than 10 deformation cycles,the shape memory polymer composites(SMPCs)could be used for deployable structure and releasing mechanism.In this paper,without traditional electro-explosive devices or motors/controllers,the deployable SMPC flexible solar array system(SMPC-FSAS)is studied,developed,ground-based tested,and finally on-orbit validated.The epoxy-based SMPC is used for the rolling-out variable-stiffness beams as a structural frame as well as an actuator for the flexible blanket solar array.The releasing mechanism is primarily made of the cyanate-based SMPC,which has a high locking stiffness to withstand 50 g gravitational acceleration and a large unlocking displacement of 10 mm.The systematical mechanical and thermal qualification tests of the SMPC-FSAS flight hardware were performed,including sinusoidal sweeping vibration,shocking,acceleration,thermal equilibrium,thermal vacuum cycling,and thermal cycling test.The locking function of the SMPC releasing mechanisms was in normal when launching aboard the SJ20 Geostationary Satellite on 27 Dec.,2019.The SMPC-FSAS flight hardware successfully unlocked and deployed on 5 Jan.,2020 on geostationary orbit.The triggering signal of limit switches returned to ground at the 139 s upon heating,which indicated the successful unlocking function of SMPC releasing mechanisms.A pair of epoxy-based SMPC rolled variable-stiffness tubes,which clapped the flexible blanket solar array,slowly deployed and finally approached an approximate 100%shape recovery ratio within 60 s upon heating.The study and on-orbit successful validation of the SMPC-FSAS flight hardware could accelerate the related study and associated productions to be used for the next-generation releasing mechanisms as well as space deployable structures,such as new releasing mechanisms with low-shocking,testability and reusability,and ultra-large space deployable solar arrays.

Reinforced cathode-garnet interface for high-capacity all-solid-state batteries

Garnet-type solid-state electrolytes(SSEs)are particularly attractive in the construction of all-solid-state lithium(Li)batteries due to their high ionic conductivity,wide electrochemical window and remarkable(electro)chemical stability.However,the intractable issues of poor cathode/garnet interface and general low cathode loading hinder their practical application.Herein,we demonstrate the construction of a reinforced cathode/garnet interface by spark plasma sintering,via co-sintering Li_(6.5)La_(3)Zr_(1.5)Ta_(0.5)O_(12)(LLZTO)electrolyte powder and LiCoO_(2)/LLZTO composite cathode powder directly into a dense dual-layer with 5 wt%Li_(3)BO_(3)as sintering additive.The bulk composite cathode with LiCoO_(2)/LLZTO cross-linked structure is firmly welded to the LLZTO layer,which optimizes both Li-ion and electron transport.Therefore,the one-step integrated sintering process implements an ultra-low cathode/garnet interfacial resistance of 3.9Ωcm^(2)(100◦C)and a high cathode loading up to 2.02 mAh cm^(−2).Moreover,the Li_(3)BO_(3)reinforced LiCoO_(2)/LLZTO interface also effectively mitigates the strain/stress of LiCoO_(2),which facilitates the achieving of superior cycling stability.The bulk-type Li|LLZTO|LiCoO_(2)-LLZTO full cell with areal capacity of 0.73 mAh cm^(−2)delivers capacity retention of 81.7%after 50 cycles at 100μA cm^(−2).Furthermore,we reveal that non-uniform Li plating/stripping leads to the formation of gaps and finally results in the separation of Li and LLZTO electrolyte during long-term cycling,which becomes the dominant capacity decay mechanism in high-capacity full cells.This work provides insight into the degradation of Li/SSE interface and a strategy to radically improve the electrochemical performance of garnet-based all-solid-state Li batteries.

High performance solid-state thermoelectric energy conversion via inorganic metal halide perovskites under tailored mechanical deformation

Solid-state thermoelectric energy conversion devices attract broad research interests because of their great promises in waste heat recycling,space power generation,deep water power generation,and temperature control,but the search for essential thermoelectric materials with high performance still remains a great challenge.As an emerging low cost,solution-processed thermoelectric material,inorganic metal halide perovskites CsPb(I_(1–x)Br_(x))_(3) under mechanical deformation is systematically investigated using the first-principle calculations and the Boltzmann transport theory.It is demonstrated that halogen mixing and mechanical deformation are efficient methods to tailor electronic structures and charge transport properties in CsPb(I_(1–x)Br_(x))_(3) synergistically.Halogen mixing leads to band splitting and anisotropic charge transport due to symmetry-breakinginduced intrinsic strains.Such band splitting reconstructs the band edge and can decrease the charge carrier effective mass,leading to excellent charge transport properties.Mechanical deformation can further push the orbital energies apart from each other in a more controllable manner,surpassing the impact from intrinsic strains.Both anisotropic charge transport properties and ZT values are sensitive to the direction and magnitude of strain,showing a wide range of variation from 20%to 400%(with a ZT value of up to 1.85)compared with unstrained cases.The power generation efficiency of the thermoelectric device can reach as high as approximately 12%using mixed halide perovskites under tailored mechanical deformation when the heat-source is at 500 K and the cold side is maintained at 300 K,surpassing the performance of many existing bulk thermoelectric materials.

In situ formed synaptic Zn@LiZn host derived from ZnO nanofiber decorated Zn foam for dendrite-free lithium metal anode

Lithium metal is regarded as the most promising anode material for next generation high energy density lithium batteries due to its high theoretical capacity and lowest potential versus standard hydrogen electrode.However,lithium dendrite growth and huge volume change during cycling hinder its practical application.It is of great importance to design advanced Li metal anodes to solve these problems.Herein,we report a ZnO-coated Zn foam as the host matrix to pre-store lithium through thermal infusing,achieving a Zn@ZnO foam supported Li composite electrode(LZO).Needlelike ZnO nanofibers grown on the Zn foam greatly increase the surface area and enhance the lithiophilicity of the Zn foam.In situ formed synaptic LiZn layer after lithium infusion can disperse local current density and lower Li diffusion barrier effectively,leading to homogeneous Li deposition behavior,thus suppressing dendrite formation.The porous Zn foam skeleton can accommodate volume variation of the electrode during longterm cycling.Benefiting from these merits,the LZO anode exhibits much better cycle stability and rate capability in both symmetrical and full cells with low voltage hysteresis than the bare Li anode.This work opens a new opportunity in designing high performance composite Li anode for lithium-metal batteries.