Multifunctional Layer Research Articles

NaF-Rich Multifunctional Layers toward Stable All-Solid-State Sodium Batteries.

NASICON oxide solid electrolytes are considered promising candidates for all-solid-state sodium batteries due to their extremely high ionic conductivity and favorable electrochemical stability. However, the practical application of NASICON electrolytes is greatly impeded by poor electrolyte-electrode interfacial contact and continuous sodium dendrite propagation. Herein, a NaF-rich multifunctional interface layer on the surface of a Na anode (Na@NaF-rich), containing NaF, amorphous carbon, and an unreacted C-F bond species, is developed in situ by the reaction between Na and commercial poly(tetrafluoroethylene). This NaF-rich interface layer is proven to reduce the diffusion barriers at the Na/NASICON electrolyte interface and homogenize Na deposition as well as suppress Na dendrite growth, thus achieving a high critical current density of 4 mA cm-2. The resultant Na3V2(PO4)3@C/Na@NaF-rich all-solid-state cell showed a high initial specific capacity of 117.6 mAh g-1 at 0.1 C with a Coulombic efficiency of 94.8%. Even at 0.5 and 1 C, it still exhibited high capacity retentions of 83.3% and 80.4%, respectively, after 750 cycles.

Ultrastable Sodium/Potassium Metal Anode Enabled by a Multifunctional Interphase Layer with Enhanced Ion Transport Kinetics

AbstractNa (K) metal batteries (NMB and KMB) have gained tremendous attention as large‐scale energy storage systems because of their high specific capacity, low working potential, and natural abundance. However, severe Na dendrite growth hinders the practical application of Na (K) anode. Here, a multifunctional interphase layer consisting of fast‐ion conductive Na–Bi (K–Bi) alloy and sodiophilic (potassiophilic) Na3VO4 (K3VO4) phases, which i derived from a spontaneous reaction (denoted as BVO@Na or BVO@K), is proposed and prepared. The designed electrode exhibits enhanced ion transport kinetics and homogenous Na (K) deposition behavior, and finally achieving dendrite‐free Na (K) growth. Accordingly, the BVO@Na displays a high Na plating/stripping reversibility of 960 h at 1.0 mA cm−2, 1.0 mAh cm−2, and the BVO@K electrode can be operated a cycle lifespan of 870 h under 1.0 mA cm−2, 2.0 mAh cm−2 in symmetric cells. In BVO@Na||Na3V2(PO4)3 full battery, it shows remarkable cycling stability (91% of capacity retention after 1900 cycles) and a high energy density of 281 Wh kg−1 at a power density of 16.2 kW kg−1. The findings lend credence to the prospect of the multifunctional interface layer contributing to the design of a protective layer for alkali metal anodes.

Sputtering of Molybdenum as a Promising Back Electrode Candidate for Superstrate Structured Sb2 S3 Solar Cells.

Sb2 S3 is rapidly developed as light absorber material for solar cells due to its excellent photoelectric properties. However, the use of the organic hole transport layer of Spiro-OMeTAD and gold (Au) in Sb2 S3 solar cells imposes serious problems in stability and cost. In this work, low-cost molybdenum (Mo) prepared by magnetron sputtering is demonstrated to serve as a back electrode in superstrate structured Sb2 S3 solar cells for the first time. And a multifunctional layer of Se is inserted between Sb2 S3 /Mo interface by evaporation, which plays vital roles as: i) soft loading of high-energy Mo particles with the help of cottonlike-Se layer; ii) formation of surficial Sb2 Se3 on Sb2 S3 layer, and then reducing hole transportation barrier. To further alleviate the roll-over effect, a pre-selenide Mo target and consequentially form a MoSe2 is skillfully sputtered, which is expected to manipulate the band alignment and render an enhanced holes extraction. Impressively, the device with an optimized Mo electrode achieves an efficiency of 5.1%, which is one of the highest values among non-noble metal electrode based Sb2 S3 solar cells. This work sheds light on the potential development of low-cost metal electrodes for superstrate Sb2 S3 devices by carefully designing the back contact interface.

The Organic Ligand Etching Method for Constructing In Situ Terraced Protective Layer Toward Stable Aqueous Zn Anode.

The stability of aqueous Zn-ion batteries (AZIBs) is highly dependent on the reversibility of stripping/plating Zn anode. In this work, an organic ligand etching method is proposed to develop a series of in situ multifunctional protective layers on Zn anode. Particularly, the 0.02m [Fe(CN) 6]3- etching solutions can spontaneously etch the Zn anode, creating an in situ protective layer with unique terraced structure, which blocks the direct contact between the electrode and electrolyte and increases the area for Zn2+ ions deposition. Interestingly, all elements in the organic ligands (i.e., C, N, Zn, and Fe) exhibit strong zincophilic, significantly promoting zinc deposition kinetics and enhancing 3D nucleation behavior to inhibit zinc dendrite growth. As a result, the etched Zn anode can provide as high a Coulombic efficiency of 99.6% over 1000 cycles and sustain over 400 h long-term stability at a high current density of 10mA cm-2 . As general validation, the small amount of metal cations additives (e.g., Ni2+ , Mn2+ , and Cu2+ ) can accelerate the synthesis of artificial interface layers with 3D structures and also regulate zinc deposition behavior. This work provides a new idea from the perspective of etching solution selection for surface modification of Zn metal anode.

Ni-Epoxy/Ni Multifunctional Layer Integrated Perovskite-Based Photoanode with High Electric Field

Ni-Epoxy/Ni Multifunctional Layer Integrated Perovskite-Based Photoanode with High Electric Field

3D printed epoxy composite microsandwich with high strength, toughness, and EMI shielding performances

Materials with exceptional mechanical and electromagnetic interference (EMI) shielding properties are urgently needed due to the growing demand for multifunctional protection layers in aviation and new energy vehicles. Herein, we fabricate an epoxy-based composite microsandwich composing of solid and lattice layers via 3D printing. The rationally assembled layered architecture together with high manufacturing accuracy give the microsandwich high strength, toughness, and fracture toughness, exhibiting 92%, 140%, and 18.5% improvement compared to its solid counterpart, respectively. The solid layers bear most of the loadings, while the cellular lattice layers can prevent quick crack propagation, resulting in simultaneously high strength and toughness. Besides, the synergetic effect of the solid and lattice layers also effectively promotes the multiple reflection of the incident electromagnetic waves, giving rise to a high EMI shielding effectiveness. The above findings might offer insights into the achievement of highly tunable multifunctional properties for epoxy-based composites through properly controlled architectures.

Regulated Zn Plating and Stripping by a Multifunctional Polymer-Alloy Interphase Layer for Stable Zn Metal Anode.

Metallic zinc electrode with a high theoretical capacity of 820mAhg-1 is highly considered as a promising candidate for next-generation rechargeable batteries. However, the unavoidable hydrogen evolution, uncontrolled dendrite growth, and severe passivation reaction badly hinder its practical implementations. Herein, a robust polymer-alloy artificial protective layer is designed to realize dendrite-free Zn metal anode by the integration of zincophilic SnSb nanoparticles with Nafion. In comparison to the bare Zn electrode, the Nafion-SnSb coated Zn (NFSS@Zn) electrode exhibits lower nucleation energy barrier, more uniform electric field distribution and stronger anti-corrosion capability, thus availably suppressing the Zn dendrite growth and interfacial side reactions. As a consequence, the NFSS@Zn electrode exhibits a long cycle life over 1500h at 1mAcm-2 with an ultra-low voltage hysteresis (25mV). Meanwhile, when paired with a MnO2 cathode, the as-prepared full cell also demonstrates stable performance for 1000cycles at 3Ag-1 . This work provides an inspired approach to boost the performance of Zn anodes.

Fluorinated Graphene-Lewis-Base Polymer Composites as a Multifunctional Passivation Layer for High-Performance Perovskite Solar Cells.

Increasing the open-circuit voltage (Voc) stands as a critical strategy for further improving the efficiency of organic-inorganic halide perovskite solar cells (PSCs). Lewis basic polymers, such as polymethyl methacrylate (PMMA), are considered as an effective approach to reduce the nonradiative recombination at the perovskite surface and protect the photoactive layer against moisture. However, the insulating nature of PMMA inherently leads to increased series resistance in PSCs. Here, we propose a multifunctional passivation layer (FG-PMMA) composed of fluorinated graphene (FG) and PMMA, offering high conductivity, a good passivation effect, and excellent hole transportation capabilities. The introduction of FG not only reduces the resistance of the PMMA layer but also improves its hydrophobicity. More importantly, we found that fluoride, which acts as a p-type dopant in graphene, can further reduce the nonradiative recombination centers by forming PbF2 with uncoordinated Pb0 at the perovskite/hole transport layer interface. As a result, the introduction of FG-PMMA significantly enhances the photovoltaic performance, with a record-high open-circuit voltage (Voc) of 1.247 V and an average power conversion efficiency of 22.91%, higher than those of PMMA-based devices (20.75%, 1.210 V), as well as increasing the device's moisture stability, with over 90% of the initial efficiency maintained after 1200 h of aging at room temperature and a relative humidity of 35%.

Influence of MXene-assisted multifunctional interface on zinc deposition toward highly reversible dendrite-free zinc anodes

The ever-growing demand for safe and renewable energy storage systems has driven the renaissance of aqueous zinc (Zn)-metal batteries (ZMBs). Zn metal has the characteristics of high specific capacity, low cost, environmental friendliness, and intrinsic safety, but severe side reactions and Zn dendrite growth lead to low Coulombic efficiency and short cycle life of Zn metal anode, which restricts the commercial development of rechargeable aqueous ZMBs. Herein, a Ti3C2Tx MXene-derived ZnF2-rich multifunctional interfacial layer is prepared. In this architecture, the as-formed ZnF2-rich layer can redistribute Zn-ion flux on the electrode/electrolyte surface and suppress side reactions. Meanwhile, the results indicate that the ZnF2 can lower the desolvation energy barrier of Zn ions and enhance the Zn-ion transfer kinetics. Accordingly, the Zn@MXene anode delivers a long cycle life over 800 h at the current density of 5.0 mA cm−2 with a capacity of 5.0 mAh cm−2. Surprisingly, the Zn@MXene anode can still achieve dendrite-free Zn deposition for more than 320 h even at the current density of 10.0 mA cm−2 with a capacity of 10.0 mAh cm−2. Additionally, the assembled Zn@MXene//VO2 full-cell exhibits better cycling stability and more excellent rate performance compared to the pristine Zn//VO2 full-cell, implying the potential of this idea to develop high-power rechargeable aqueous Zn-ion batteries.

Multifunctional and multi-site interfacial buffer layer for efficient and stable perovskite solar cells

Perovskite solar cells (PSCs) have achieved significant success in power conversion efficiency (PCE) and stability. However, interfacial recombination and film defects still hinder the improvement of PSCs efficiency. In this study, we propose a novel interfacial buffer layer material called Ethyl p-nitrobenzoate (EPN) to enhance device performance and stability. Our results demonstrate that introducing EPN improves the film's quality, reduces defect density, relieves interfacial stress, and significantly suppresses nonradiative recombination at the interface. Density functional theory (DFT) calculations confirm that EPN can effectively passivate defects in the perovskite and SnO2 films due to its multifunctionality. Finally, we achieved a high PCE of 23.16% for the target device while significantly enhancing device stability compared to the control. This work provides new insights into the development of multifunctional multi-site interfacial buffer layers for high-performance PSCs.

Multifunctional Titanium Oxide Layers in Silicon Heterojunction Solar Cells Formed via Selective Anodization

Herein, a novel strategy is introduced to reduce the consumption of scarce materials in silicon heterojunction solar cells by combining approaches for Ag replacement in the metallization and a reduction of the indium tin oxide layer thickness: a Ti layer deposited by physical vapor deposition serves both as the contact layer of a copper‐based metallization and after electrochemical oxidation as capping layer enabling the use of a thinner transparent conductive oxide. Further, the TiOx layer can build an encapsulation layer. While oxygen evolution and metal dissolution are found to be critical side reactions, a nonaqueous electrolyte is found in which these reactions can be avoided. The application on silicon heterojunction solar cells shows promising first results, exhibiting a short circuit current density of 35 mA cm−2 and a cell efficiency of close to 21% despite nonoptimized layer thicknesses.

Ultrafast van der Waals diode using graphene quantum capacitance and Fermi-level depinning.

Graphene, with superior electrical tunabilities, has arisen as a multifunctional insertion layer in vertically stacked devices. Although the role of graphene inserted in metal-semiconductor junctions has been well investigated in quasi-static charge transport regime, the implication of graphene insertion at ultrahigh frequencies has rarely been considered. Here, we demonstrate the diode operation of vertical Pt/n-MoSe2/graphene/Au assemblies at ~200-GHz cutoff frequency (fC). The electric charge modulation by the inserted graphene becomes essentially frozen above a few GHz frequencies due to graphene quantum capacitance-induced delay, so that the Ohmic graphene/MoSe2 junction may be transformed to a pinning-free Schottky junction. Our diodes exhibit much lower total capacitance than devices without graphene insertion, deriving an order of magnitude higher fC, which clearly demonstrates the merit of graphene at high frequencies.

Molybdenum disulfide (MoS2)/porous silica nanosheet composite barrier for polysulfide shuttling inhibition in lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) is the key choice for the next generation of high energy density batteries, while the shuttle effect of polysulfides greatly limits its development. Constructing a multifunctional barrier layer has been proved to be an effective method to inhibit the shuttle of polysulfides. Herein, molybdenum disulfide (MoS2)/2D porous silica nanosheets (PSN) composite is designed as the barrier layer. The surface oxygen-containing groups on both PSN and MoS2 enhance the adsorption for LiPSs, and the MoS2 plays a role of catalyst to facilitate the rapid polysulfide transformation. Meanwhile the abundant pores of PSN guide the uniform deposition of lithium on lithium metal anode, finally realizing the efficient transformation of lithium polysulfides and inhibition of lithium dendrites. The LSBs based on the MoS2/PSN barrier deliver high initial discharge capacity of 1521 mAh g−1 at 0.1 C, low decay rate of 0.056% per cycle at 2 C over 600 cycles, and outstanding rate performance with a high discharge capacity of 649 mAh g−1 at 4 C. The corresponding pouch cells show high discharge capacity and cycling stability, further demonstrating the potential application of the composite barrier in high-energy-density LSBs.

A Hexafluorophosphate‐Based Ionic Liquid as Multifunctional Interfacial Layer between High Voltage Positive Electrode and Solid‐State Electrolyte for Sodium Secondary Batteries

AbstractSodium secondary batteries have gained accolades as future energy storage devices due to their low costs and environmental benignity, but are heavily impeded by the poor anodic stabilities of most electrolytes, including solid‐state electrolytes (SSE), that render them incompatible with high‐voltage positive materials. This study reports, for the first time, a new synthesis technique using a fluorohydrogenate ionic liquid (IL)precursor to prepare a [DEME][PF6] ([DEME]+: N,N‐diethyl‐N‐methyl‐N‐(2‐methoxyethyl) ammonium) with high yield and high purity. Herein, a Na[PF6]‐[DEME][PF6] IL is formulated and subjected to a series of electrochemical tests to validate its performance in battery applications. The present IL harbors a strong oxidative stability (up to 5.2 V on Pt and >4.5 V on conductive carbon electrodes) that aids in the suppression of oxidative decompositions of one typical SSE, for example, beta alumina solid electrolyte (BASE), thereby extending their electrochemical window in hybrid SSE systems. A hybrid solid‐state Na secondary battery employing a high voltage positive electrode, Na3V2(PO4)2F3, is assembled using the BASE/IL configuration, and features energy density and superior cycling performance. This work demonstrates that sandwiching an SSE between the oxidatively stable [PF6]− IL can be an effective design for high voltage operation Na secondary batteries.

Single-walled carbon nanotubes film supported lithiated PIM-1 ultrathin selective barrier: A multifunctional layer for polypropylene separator to boost performance of Li-S batteries

The commercialization of lithium-sulfur (Li-S) batteries has been restrained mainly by lithium polysulfides (LiPSs) shuttling and sluggish electrochemical reactions. Herein, a functional separator with synergy effect between adsorption and catalysis is proposed to solve the above problems. Specifically, an ultrathin barrier layer of a functionalized intrinsic microporous polymer (Li-AOPIM-1) is coated on SWCNT gutter layer through spin coating and applied to modify the cathode side of commercial polypropylene (PP) separator. In this configuration, the robust SWCNT gutter layer with high conductivity can not only work as a physical barrier to block the macropores of PP separator, but also improve the integral conductivity, resulting in a rapid charge migration and reaction kinetics. The electronegative heteroatoms N and O in Li-AOPIM-1 top layer have strong adsorption capability to LiPSs so that modified separator can restrain the shuttle effect admirably. Moreover, the introduction of lithiated sites further enhance the lithium-ion conductivity. Accordingly, the Li-S batteries implementing this modified separator deliver stable lifespan with only 0.062% capacity fading rate per cycle after 500 cycles at 1 C and superior rate performance of 700.6 mAh g−1 at 3 C. This work will provide a feasible strategy for the practical applications of high-performance Li-S batteries.

Bilayer PVA composite film with structural color for high-performance and multifunctional sensing

Intelligent E-skins attract lots of attention for their potential in health monitoring, human-computer interaction, and soft-body robotics. In this work, a colorful multifunctional E-skin sensor with a Janus structure was constructed by solution casting of polyvinyl alcohol (PVA) with clay and carbon nanoparticles on a patterned PDMS template. The halloysite nanotubes (HNTs) and carbon nanoparticles (C) derived from Chinese ink were introduced into PVA to obtain a nano-reinforced layer (top) with structural color and multi-functional layer (bottom) for detection of pressure, temperature, and humidity. Uniformly dispersed HNTs greatly improves the mechanical properties of PVA (up to 46.8 MPa at 303.9% strain). The difference in water absorption of the two layers provides excellent sensitivity to humidity, so it can be used as contactless password unlocking, closing and blooming of bionic flowers, and humidity alarm. The device can achieve object capture and release within 12 s by turning on and off the xenon light. Furthermore, the sensor responds distinctly to pressure and can track human activities such as drinking motion and finger bending, which can also detect the temperature by resistance change. This work provides a materials design strategy for E-skin aimed to applications in robotics, artificial intelligence, prosthetics, and health monitoring.

Osmotically Delaminated Silicate Nanosheet-Coated NCM for Ultra-Stable Li+ Storage and Chemical Stability Toward Long-Term Air Exposure.

To ensure the safety and performance of lithium-ion batteries (LIBs), a rational design and optimization of suitable cathode materials are crucial. Lithium nickel cobalt manganese oxides (NCM) represent one of the most popular cathode materials for commercial LIBs. However, they are limited by several critical issues, such as transition metal dissolution, formation of an unstable cathode-electrolyte interphase (CEI) layer, chemical instability upon air exposure, and mechanical instability. In this work, coating fabricated by self-assembly of osmotically delaminated sodium fluorohectorite (Hec) nanosheets onto NCM (Hec-NCM) in a simple and technically benign aqueous wet-coating process is reported first. Complete wrapping of NCM by high aspect ratio (>10000) nanosheets is enabled through an electrostatic attraction between Hec nanosheets and NCM as well as by the superior mechanical flexibility of Hec nanosheets. The coating significantly suppresses mechanical degradation while forming a multi-functional CEI layer. Consequently, Hec-NCM delivers outstanding capacity retention for 300 cycles. Furthermore, due to the exceptional gas barrier properties of the few-layer Hec-coating, the electrochemical performance of Hec-NCM is maintained even after 6 months of exposure to the ambient atmosphere. These findings suggest a new direction of significantly improving the long-term stability and activity of cathode materials by creating an artificial CEI layer.

발광층 호스트 구조에 따른 용액공정 기반 저분자 유기 발광 다이오드의 소자 거동

A method for achieving efficient and stable solution-processed small-molecule organic light-emitting diodes (OLEDs) is presented by utilizing a combination of a multifunctional hole injection layer (HIL) and a mixed-host emitting layer (EML). The polymeric HIL facilitates efficient hole injection into the solution-processed EML and blocks electrons from the EML through self-organization of polymer chains in the HIL. In addition to the multifunctional HIL, the optimized mixed-host EML, composed of electron and hole transporting host materials, along with phosphorescent dopant, enables efficient energy transfer, balanced charge transport, and efficient charge carrier recombination in the device. As a result, it improves luminance (~14,000 cd/m2), luminous efficiency (~55 cd/A), and operational lifetime (~180 minutes under constant current emitting initial luminance of 1,000 cd/m2, equivalent to approximately 150 hours at an initial luminance of 100 cd/m2). Notably, this device architecture does not include an additional hole transporting/electron blocking layer. This is because the introduction of a mixed-host composition widens the recombination zone in the EML, effectively preventing triplet-triplet excitons/triplet-polaron annihilation caused by charge carriers and excitons accumulated at the narrow heterointerfaces in OLEDs.

A Multifunctional Molecular Bridging Layer for High Efficiency, Hysteresis‐Free, and Stable Perovskite Solar Cells

AbstractAt present, the dominating electron transport material (ETL) and hole transport material (HTL) used in the state‐of‐the‐art perovskite solar cells (PSCs) are tin oxide and 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)‐9,9′‐spirobifluorene (Spiro‐OMeTAD). However, the surface hydroxyl groups of the SnO2 layer and the Li+ ions within the Spiro‐OMeTAD HTL layer generally cause surface charge recombination and Li+ migration, significantly reducing the devices' performance and stability. Here, a molecule bridging layer of 3,5‐bis(fluorosulfonyl)benzoic acid (FBA) is introduced onto the SnO2 surface, which provides appropriate surface energy, reduces interfacial traps, forms a better energy level alignment, and, most importantly, anchors (immobilizes) Li+ ions in the ETL, and consequently improves the device power conversion efficiency (PCE) up to 24.26% without hysteresis. Moreover, the device with the FBA passivation layer shows excellent moisture and operational stability, maintaining over 80% of the initial PCE after 1000 h under both aging conditions. The current work provides a comprehensive understanding of the influence of the extrinsic Li+ ion migration within the cell on the device's performance and stability, which helps design and fabricate high‐performance and hysteresis‐free PSCs.

Chelate-Capped Nano-AgZn3 Dual Interphase Remodeling the Local Environment for Reversible Dendrite-Free Zinc Anode.

Rechargeable aqueous zinc-ion batteries (AZIBs) are among the most promising candidates for next-generation energy-storage devices. However, the large voltage polarisation and infamous dendrite growth hinder the practical application of AZIBs owing to their complex interfacial electrochemical environment. In this study, a hydrophobic zinc chelate-capped nano-silver (HZC-Ag) dual interphase is fabricated on the zinc anode surface using an emulsion-replacement strategy. The multifunctional HZC-Ag layer remodels the local electrochemical environment by facilitating the pre-enrichment and de-solvation of zinc ions and inducing homogeneous zinc nucleation, thus resulting in reversible dendrite-free zinc anodes. The zinc deposition mechanism on the HZC-Ag interphase is elucidated by density functional theory (DFT) calculations, dual-field simulations, and in situ synchrotron X-ray radiation imaging. The HZC-Ag@Zn anode exhibited superior dendrite-free zinc stripping/plating performance and an excellent lifespan of >2000h with ultra-low polarisation of ≈17mV at 0.5mA cm-2 . Full cells coupled with a MnO2 cathode showed significant self-discharge inhibition, excellent rate performance, and improved cycling stability for >1000 cycles. Therefore, this multifunctional dual interphase may contribute to the design and development of dendrite-free anodes for high-performance aqueous metal-based batteries.