Achieving high-capacity and long-life K^(+)storage enabled by constructing yolk-shell Sb_(2)S_(3)@N,S-doped carbon nanorod anodes

As promising anode candidates for potassium-ion batteries(PIBs),antimony sulfide(Sb_(2)S_(3))possesses high specific capacity but suffers from massive volume expansion and sluggish kinetics due to the large K^(+)insertion,resulting in inferior cycling and rate performance.To address these challenges,a yolk-shell structured Sb_(2)S_(3)confined in N,S co-doped hollow carbon nanorod(YS-Sb_(2)S_(3)@NSC)working as a viable anode for PIBs is proposed.As directly verified by in situ transmission electron microscopy(TEM),the buffer space between the Sb_(2)S_(3)core and thin carbon shell can effectively accommodate the large expansion stress of Sb_(2)S_(3)without cracking the shell and the carbon shell can accelerate electron transport and K^(+)diffusion,which plays a significant role in reinforcing the structural stability and facilitating charge transfer.As a result,the YS-Sb_(2)S_(3)@NSC electrode delivers a high reversible K^(+)storage capacity of 594.58 m A h g^(-1)at 0.1 A g^(-1)and a long cycle life with a slight capacity degradation(0.01%per cycle)for 2000 cycles at 1 A g^(-1)while maintaining outstanding rate capability.Importantly,utilizing in in situ/ex situ microscopic and spectroscopic characterizations,the origins of performance enhancement and K^(+)storage mechanism of Sb_(2)S_(3)were clearly elucidated.This work provides valuable insights into the rational design of high-performance and durable transition metal sulfides-based anodes for PIBs.

Comprehensively-modified polymer electrolyte membranes with multifunctional PMIA for highly-stable all-solid-state lithium-ion batteries

Polyethylene oxide(PEO)-based electrolytes have obvious merits such as strong ability to dissolve salts(e.g.,LiTFSI)and high flexibility,but their applications in solid-state batteries is hindered by the low ion conductance and poor mechanical and thermal properties.Herein,poly(m-phenylene isophthalamide)(PMIA)is employed as a multifunctional additive to improve the overall properties of the PEO-based electrolytes.The hydrogen-bond interactions between PMIA and PEO/TFSI-can effectively prevent the PEO crystallization and meanwhile facilitate the LiTFSI dissociation,and thus greatly improve the ionic conductivity(two times that of the pristine electrolyte at room temperature).With the incorporation of the high-strength PMIA with tough amide-benzene backbones,the PMIA/PEO-LiTFSI composite polymer electrolyte(CPE)membranes also show much higher mechanical strength(2.96 MPa),thermostability(4190℃)and interfacial stability against Li dendrites(468 h at 0.10 mA cm-2)than the pristine electrolyte(0.32 MPa,364℃and short circuit after 246 h).Furthermore,the CPE-based LiFePO4/Li cells exhibit superior cycling stability(137 mAh g^-1 with 93%retention after 100 cycles at 0.5 C)and rate performance(123 mAh g^-1 at 1.0 C).This work provides a novel and effective CPE structure design strategy to achieve comprehensively-upgraded electrolytes for promising solid-state battery applications.

LiPO_(2)F_(2) electrolyte additive for high-performance Li-rich cathode material

Li-rich layered oxide cathodes have received considerable attention because of the high operating potential and specific capacity. However, the structural instability and parasitic reactions at high potential cause severe degradation of the electrochemical performance. In our studies, the cycling stability of Li_(1.14)Ni_(0.133)Co_(0.133)Mn_(0.544)O_(2) cathode is improved with LiPO_(2)F_(2) electrolyte additive. After 500 cycles, the capacity retention is increased from 53.6% to 85% at 3 C by LiPO_(2)F_(2) modification. This performance is mainly attributed to the enhanced interfacial stability of the Li-rich cathode. Based on systematic characterization, LiPO_(2)F_(2) additive was found to promote a stable interface film on the cathode surface during the cycling and mitigates the interfacial side reactions. This study provides new insights for improving high-potential Li-rich layered oxide batteries.

Effect of Annealing Temperature on the Formation of Silicides and the Surface Morphologies of PtSi Films

The effect of annealing temperature on the formation of the PtSi phase. distribution of silicides and the surface morphologies of silicides films is investigated by XPS. AFM. It is shown that the phase sequences of the films change from Pt-Pt2Si-PtSi-Si to Pt+Pt2Si+PtSi-PtSi-Si or Pt+Pt2Si+PtSi-PtSi-st with an increase of annealing temperature and the reason for the formation of mixed layers is discussed.

Flexible ion-conducting membranes with 3D continuous nanohybrid networks for high-performance solid-state metallic lithium batteries

Polyethylene oxide(PEO)-based electrolytes are considered as one of the most promising solid-state electrolytes for next-generation lithium batteries with high safety and energy density;however,the drawbacks such as insufficient ion conductance,mechanical strength and electrochemical stability hinder their applications in metallic lithium batteries.To enhance their overall properties,flexible and thin composite polymer electrolyte(CPE)membranes with 3D continuous aramid nanofiber(ANF)–Li_(1.4)Al_(0.4)Ti_(1.6)(PO_(4))_(3)(LATP)nanoparticle hybrid frameworks are facilely prepared by filling PEO–Li TFSI in the 3D nanohybrid scaffolds via a solution infusion way.The construction of the 3D continuous nanohybrid networks can effectively inhibit the PEO crystallization,facilitate the lithium salt dissociation and meanwhile increase the fast-ion transport in the continuous LATP electrolyte phase,and thus greatly improving the ionic conductivity(~3 times that of the pristine one).With the integration of the 3D continuity and flexibility of the 3D ANF networks and the thermostability of the LATP phase,the CPE membranes also show a wider electrochemical window(~5.0 V vs.4.3 V),higher tensile strength(~4–10times that of the pristine one)and thermostability,and better lithium dendrite resistance capability.Furthermore,the CPE-based Li FePO_(4)/Li cells exhibit superior cycling stability(133 m Ah/g after 100 cycles at 0.3 C)and rate performance(100 m Ah/g at 1 C)than the pristine electrolyte-based cell(79 and 29m Ah/g,respectively).This work offers an important CPE design criteria to achieve comprehensivelyupgraded solid-state electrolytes for safe and high-energy metal battery applications.

Nanostructured AlFeO_(3) thin films as a novel photoanode for photoelectrochemical water splitting

The earth-abundant and robust aluminum ferrite,AlFeO_(3)(AFO),is mainly studied in the context of ferroelectrics.Herein,we demonstrate that AFO can be used as a stable solar absorber in photoelectrochemical cells for solar water splitting,exhibiting attractive performance.This is the first report on the photoelectrochemical activity of AFO.AFO thin-film photoelectrodes prepared by solution-processing methods are composed of vertically oriented thin nanosheets,featuring the rhombohedral symmetry(R3c)and n-type conductivity.The as-prepared AFO photoanodes generate a photocurrent density of+0.78 mA·cm^(-2) at 1.23 V vs.reversible hydrogen electrode(RHE)with the photocurrent _(onset) potential(U_(onset))close to the flat band potential of 0.5 V vs.RHE in the presence of hole scavengers.Remarkably,the U_(onset) of AFO for solar water splitting coincides with the flat band potential as well,which is rare in n-type inorganic absorbers.We also report other properties of AFO associated with photoelectrochemical performance.AFO films exhibit a band gap energy of 2.31 eV and positive band edges with low dispersion.Moreover,the carrier lifetimes in AFO films are up to millisecond timescales under the mediation of defect traps.Based on the photoelectrochemical behavior and optoelectronic properties,we believe that AFO has great potential for application in photoelectrochemical cells.

Vinyltrimethylsilane as a novel electrolyte additive for improving interfacial stability of Li-rich cathode working in high voltage

Boosting the interfacial stability between electrolyte and Li-rich cathode material at high operating voltage is vital important to enhance the cycling stability of Li-rich cathode materials for high-performance Li-ion batteries.In this work,vinyltrimethylsilane as a new type of organic silicon electrolyte additive is studied to address the interfacial instability of Li-rich cathode material at high operating voltage.The cells using vinyltrimethylsilane additive shows the high capacity retention of 73.9%after 300 cycles at 1 C,whereas the cells without this kind of additive only have the capacity retention of 58.9%.The improvement of stability is mainly attributed to the additive helping to form a more stable surface film for Li-rich cathode material,thus avoiding direct contact between the electrolyte and the cathode material,slowing down the dissolution of metal ions and the decomposition of the electrolyte under high operating voltage.Our findings in this work shed some light on the design of stable cycling performance of Li-rich cathode toward advanced Li-ion batteries.

Computational Study of Ternary Devices: Stable, Low-Cost,and Efficient Planar Perovskite Solar Cells

Although perovskite solar cells with power conversion efficiencies(PCEs) more than 22% have been realized with expensive organic charge-transporting materials, their stability and high cost remain to be addressed. In this work, the perovskite configuration of MAPbX(MA = CH_3 NH_3,X = I_3, Br_3, or I_2Br) integrated with stable and low-cost Cu:Ni Oxhole-transporting material, ZnO electron-transporting material, and Al counter electrode was modeled as a planar PSC and studied theoretically. A solar cell simulation program(wx AMPS), which served as an update of the popular solar cell simulation tool(AMPS: Analysis of Microelectronic and Photonic Structures), was used. The study yielded a detailed understanding of the role of each component in the solar celland its effect on the photovoltaic parameters as a whole. The bandgap of active materials and operating temperature of the modeled solar cell were shown to influence the solar cell performance in a significant way. Further, the simulation results reveal a strong dependence of photovoltaic parameters on the thickness and defect density of the light-absorbing layers. Under moderate simulation conditions, the MAPb Br_3 and MAPbI _2 Br cells recorded the highest PCEs of 20.58 and 19.08%, respectively, while MAPbI_3 cell gave a value of 16.14%.

TiO_(2)bunchy hierarchical structure with effective enhancement in sodium storage behaviors

Bronze phase TiO_(2)[TiO_(2)(B)]has great research potential for sodium storage since it has a higher theoretical capacity and ion mobility compared with other phases of TiO_(2).In this case,preparing porous TiO_(2)(B)nanosheets,which can provide abundant sodium insertion channels,is the most effective way to improve transport kinetics.Here,we use the strong one-dimensional TiO_(2)nanowires as the matrix for stringing these nanosheets together through a simple solvothermal method to build a bunchy hierarchical structure[TiO_(2)(B)-BH],which has fast pseudocapacitance behavior,high structural stability,and effective ion/electron transport.With the superiorities of this structure design,TiO_(2)(B)-BH has a higher capacity(131 vs.70 mAh g^(−1)[TiO_(2)-NWs]at 0.5 C).And it is worth mentioning that the reversible capacity of up to 500 cycles can still be maintained at 85 mAh g^(−1)at a high rate of 10 C.Meanwhile,we also further analyzed the sodium storage mechanism through the ex-situ X-ray powder diffraction test,which proved the high structural stability of TiO_(2)(B)-BH in the process of sodiumization/de-sodiumization.This strategy of uniformly integrating nanosheets into a matrix can also be extended to preparing electrode material structures of other energy devices.

Solid electrolyte interphase on anodes in rechargeable lithium batteries

Highly safe and efficient rechargeable lithium batteries have become an indispensable component of the intelligent society powering smart electronics and electric vehicles.This review summarizes the formation principle,chemical compositions,and theoretical models of the solid electrolyte interphase(SEI)on the anode in the lithium battery,involving the functions and influences of the electroactive materials.The discrepancies of the SEI on different kinds of anode materials,as well as the choice and design of the electrolytes are detailedly clarified.Furthermore,the design strategies to obtain a stable and efficient SEI are outlined and discussed.Last but not least,the challenges and perspectives of artificial SEI technology are briefly proposed for the development of high-efficiency batteries in practice.

Building better solid-state batteries with silicon-based anodes

Silicon(Si)-based solid-state batteries(Si-SSBs)are attracting tremendous attention because of their high energy density and unprecedented safety,making them become promising candidates for next-generation energy storage systems.Nevertheless,the commercialization of Si-SSBs is significantly impeded by enormous challenges including large volume variation,severe interfacial problems,elusive fundamental mechanisms,and unsatisfied electrochemical performance.Besides,some unknown electrochemical processes in Si-based anode,solid-state electrolytes(SSEs),and Si-based anode/SSE interfaces are still needed to be explored,while an in-depth understanding of solid–solid interfacial chemistry is insufficient in Si-SSBs.This review aims to summarize the current scientific and technological advances and insights into tackling challenges to promote the deployment of Si-SSBs.First,the differences between various conventional liquid electrolyte-dominated Si-based lithium-ion batteries(LIBs)with Si-SSBs are discussed.Subsequently,the interfacial mechanical contact model,chemical reaction properties,and charge transfer kinetics(mechanical–chemical kinetics)between Si-based anode and three different SSEs(inorganic(oxides)SSEs,organic–inorganic composite SSEs,and inorganic(sulfides)SSEs)are systemically reviewed,respectively.Moreover,the progress for promising inorganic(sulfides)SSE-based Si-SSBs on the aspects of electrode constitution,three-dimensional structured electrodes,and external stack pressure is highlighted,respectively.Finally,future research directions and prospects in the development of Si-SSBs are proposed.

Solid polymer electrolytes:Ion conduction mechanisms and enhancement strategies

Solid polymer electrolytes(SPEs)possess comprehensive advantages such as high flexibility,low interfacial resistance with the electrodes,excellent film-forming ability,and low price,however,their applications in solid-state batteries are mainly hindered by the insufficient ionic conductivity especially below the melting temperatures,etc.To improve the ion conduction capability and other properties,a variety of modification strategies have been exploited.In this review article,we scrutinize the structure characteristics and the ion transfer behaviors of the SPEs(and their composites)and then disclose the ion conduction mechanisms.The ion transport involves the ion hopping and the polymer segmental motion,and the improvement in the ionic conductivity is mainly attributed to the increase of the concentration and mobility of the charge carriers and the construction of fast-ion pathways.Furthermore,the recent advances on the modification strategies of the SPEs to enhance the ion conduction from copolymer structure design to lithium salt exploitation,additive engineering,and electrolyte micromorphology adjustion are summarized.This article intends to give a comprehensive,systemic,and profound understanding of the ion conduction and enhancement mechanisms of the SPEs for their viable applications in solid-state batteries with high safety and energy density.

Excellent light-capture capability of trilobal SiNW for ultra-high JSC in single-nanowire solar cells

Single-.nanowire solar cells with a unique light-concentration property are expected to exceed the Shockley-Queisser limit.The architecture of single nanowire is an important factor to regulate its optical performance.We designed a trilobal silicon nanowire(SiNW)with two cquivalent scales that possesses superior light-absorption efficiency in the whole wavelength range and shows good tolerance for incident angle.The electric field distribution in this geometry is concentrated in the blade with small equivalent scale and pivot with large equivalent scale,respectively,in the short wavelength range and long wavelength range.Corresponding good light absorption of trilobal SiNW in the two wavelength ranges leads to stronger total light absorption capacity than that of cylindrical SiNW.Trilobal single nanowire solar cells can obtain a short-circuit current density(JSC)of 647 mA·cm^2,which provides a new choice for designing single nanowire with excellent light-capture capability.

Designing novel thin film polycrystalline solar cells for high efficiency:sandwich CIGS and heterojunction perovskite

Heterojunction and sandwich architectures are two new-type structures with great potential for solar cells.Specifically,the heterojunction structure possesses the advantages of efficient charge separation but suffers from band offset and large interface recombination;the sandwich configuration is favorable for transferring carriers but requires complex fabrication process.Here,we have designed two thin-film polycrystalline solar cells with novel structures：sandwich CIGS and heterojunction perovskite,referring to the advantages of the architectures of sandwich perovskite（standard）and heterojunction CIGS（standard）solar cells,respectively.A reliable simulation software wxAMPS is used to investigate their inherent characteristics with variation of the thickness and doping density of absorber layer.The results reveal that sandwich CIGS solar cell is able to exhibit an optimized efficiency of 20.7%,which is much higher than the standard heterojunction CIGS structure（18.48%）.The heterojunction perovskite solar cell can be more efficient employing thick and doped perovskite films（16.9%）than these typically utilizing thin and weak-doping/intrinsic perovskite films（9.6%）.This concept of structure modulation proves to be useful and can be applicable for other solar cells.

Resistive-type sensors based on few-layer MXene and SnO_(2)hollow spheres heterojunctions:Facile synthesis,ethanol sensing performances

High-performance and low-cost gas sensors are highly desirable and involved in industrial production and environmental detection.The combination of highly conductive MXene and metal oxide materials is a promising strategy to further improve the sensing performances.In this study,the hollow SnO_(2)nanospheres and few-layer MXene are assembled rationally via facile electrostatic synthesis processes,then the SnO_(2)/Ti_(3)C_(2)T_(x)nanocomposites were obtained.Compared with that based on either pure SnO_(2)nanoparticles or hollow nanospheres of SnO_(2),the SnO_(2)/Ti_(3)C_(2)T_(x)composite-based sensor exhibits much better sensing performances such as higher response(36.979),faster response time(5 s),and much improved selectivity as well as stability(15 days)to 100ppm C2H5OH at low working temperature(200°C).The improved sensing performances are mainly attributed to the large specific surface area and significantly increased oxygen vacancy concentration,which provides a large number of active sites for gas adsorption and surface catalytic reaction.In addition,the heterostructure interfaces between SnO_(2)hollow spheres and MXene layers are beneficial to gas sensing behaviors due to the synergistic effect.

In-situ Observation of Crack Growth and Domain Switching Around Vickers Indentation on BaTiO_3 Single Crystal Under Sustained Electric Field

The crack propagation and domain switching process around the indentation on the surface of barium titanate single crystal under the external electric field was investigated by atomic force microscope and polarized light microscope. The evolutions of domain switching and crack propagation were in-situ observed when a 90°a- c domain wall moved across the indentation which was driven by external electric field. The results show that the incompatible strain induced by domain switching in the residual stress zone around the indentation is the driving force of the anisotropic crack propagation. The crack propagation results in the changes of the fine domain stripes around the crack tip.

Preface to the SPECIAL ISSUE: Excitonic Solar Cells(II)

Among all the excitonic solar cells(ESCs)including dyesensitized solar cells(DSSCs),quantum solar cells(QDSCs),perovskites solar cells(PSCs),and organic photovoltaics(OPVs),PSCs attracted enormous research attention in the past 7 years and attained the highest power conversion efficiency(PCE)of over 20%with the biggest progress,from 3.8%to over 22.1%in 7 years.However,one can easily realize the fact that such a rapid progress achieved in PSCs was made possible is largely based on the fundamental knowledge,experimental skills,and characterization facilities obtained and accumulated through the multi-decade long endeavor in the study of other excitonic solar cells.Even though PSCs have attractedmuch research human resource and funding,the study on other excitonic solar cells has never stopped,and such persistent

Research progress in improving the performance of PEDOT:PSS/Microand Nano-textured Si heterojunction for hybrid solar cells

Silicon-based hybrid solar cells(HSCs),especially PEDOT:PSS/Si HSC,have attracted the interest of researchers because they combine the advantages of organic and inorganic materials.A high quality PEDOT:PSS/Si heterojunction is the key to the good performance of PEDOT:PSS/Si HSC.However,as generally requisite to enhance light absorption for HSCs,Si Micro/Nano structures will reduce the interface contact quality between PEDOT:PSS and Si surface.The inferior interface contact quality will limit the separation efficiency of the photogenerated carriers.In this paper,we summarize the research progress in improving the interface contact between Si Micro/Nano structures and PEDOT:PSS film from three aspects:the optimization of Si Micro/Nano structures aimed to improve the fluid properties of PEDOT:PSS solution,the material modification of PEDOT:PSS and interface modification with the purpose to enlarge the heterojunction area and improve the electrical contact,and the specific deposition process of PEDOT:PSS solution developed to achieve the high filling rate of PEDOT:PSS on Si Micro/Nano structures.The insight of this paper is helpful for the preparation of high-quality heterojunction,which is vitally important for the development of high efficiency PEDOT:PSS/Si HSCs.

Preface to the SPECI AL ISSUE: Excitonic Solar Cells(Ⅰ)

Search and development of clean sustainable energy or renewable energy become an imperative demand beyond the concerns of limited resource and cost of fossil fuels that our modern life is so much dependent on.Among all the renewable energy,solar energy is the most abundant and likely to make the most significant contribution to the clean energy efforts.Although the usage of solar energy has