Interface Issue Research Articles

Wet Chemical Method ZnF2 Interlayer for High Critical Current Density Lithium Metal Batteries Utilizing Ba and Ta–Doped Li7La3Zr2O12 Garnet Solid Electrolyte

AbstractLi metal batteries with garnet‐type solid electrolytes have the potential to increase specific energy and power densities of current Li‐ion batteries. Li metal batteries have been hampered by the poor wettability of solid electrolyte with elemental lithium. Here, to resolve the solid garnet electrolyte/Li interface issue, a scalable, cost‐effective, and efficient surfactant‐assisted wet‐chemical strategy is developed. A ZnF2 interlayer coating is applied on Ba and Ta ‐co‐doped Li7La2.75Ba0.25Zr1.75Ta0.25O12 that formed LiF and Li‐Zn alloy upon contact with molten Li. Conformal contact applying a homogenous surfactant‐assisted ZnF2 coating reduced the interfacial resistance from 87 to 15.5 Ω cm2 which enhanced critical current density to a record high value of 5 mA cm−2 at room temperature. Dense and Li2CO3 free garnet solid electrolyte assisted in achieving long‐term stability for 1000 cycles at 1 mA cm−2. Interface stabilized Li/ZnF2‐ solid electrolyte/liquid electrolyte/LiFePO4 cell displayed a 90% capacity retention over 800 cycles at 0.2 C, with Coulombic efficiency of 99% as well as excellent cycle stability at 1 C, with ≈91% of capacity retention for 500 cycles. Using a new design principle for Li anode interfaces, next‐generation power‐intensive and stable solid‐state Li metal batteries can be developed.

Solvation Regulation Reinforces Anion-Derived Inorganic-Rich Interphase for High-Performance Quasi-Solid-State Li Metal Batteries.

Solid-state polymer lithium metal batteries are an important strategy for achieving high safety and high energy density. However, the issue of Li dendrites and inherent inferior interface greatly restricts practical application. Herein, this study introduces tris(2,2,2-trifluoroethyl)phosphate solvent with moderate solvation ability, which can not only complex with Li+ to promote the in-situ ring-opening polymerization of 1,3-dioxolane (DOL), but also build solvated structure models to explore the effect of different solvation structures in the polymer electrolyte. Thereinto, it is dominated by the contact ion pair solvated structure with pDOL chain segments forming less lithium bonds, exhibiting faster kinetic process and constructing a robust anion-derived inorganic-rich interphase, which significantly improves the utilization rate of active Li and the high-voltage resistance of pDOL. As a result, it exhibits stable cycling at ultra-high areal capacity of 20 mAh cm-2 in half cells, and an ultra-long lifetime of over 2000h in symmetric cells can be realized. Furthermore, matched with LiNi0.9Co0.05Mn0.05O2 cathode, the capacity retention after 60 cycles is as high as 96.8% at N/P value of 3.33. Remarkably, 0.7 Ah Li||LiNi0.9Co0.05Mn0.05O2 pouch cell with an energy density of 461Wh kg-1 can be stably cycled for five cycles at 100% depth of discharge.

Maximizing interface stability in all-solid-state lithium batteries through entropy stabilization and fast kinetics

The positive electrode|electrolyte interface plays an important role in all-solid-state Li batteries (ASSLBs) based on garnet-type solid-state electrolytes (SSEs) like Li6.4La3Zr1.4Ta0.6O12 (LLZTO). However, the trade-off between solid-solid contact and chemical stability leads to a poor positive electrode|electrolyte interface and cycle performance. In this study, we achieve thermodynamic compatibility and adequate physical contact between high-entropy cationic disordered rock salt positive electrodes (HE-DRXs) and LLZTO through ultrafast high-temperature sintering (UHS). This approach constructs a highly stable positive electrode|electrolyte interface, reducing the interface resistance to 31.6 Ω·cm2 at 25 °C, making a 700 times reduction compared to the LiCoO2 | LLZTO interface. Moreover, the conformal and tight HE-DRX | LLZTO solid-state interface avoids the transition metal migration issue observed with HE-DRX in liquid electrolytes. At 150 °C, HE-DRXs in ASSLBs (Li|LLZTO | HE-DRXs) exhibit an average specific capacity of 239.7 ± 2 mAh/g at 25 mA/g, with a capacity retention of 95% after 100 cycles relative to the initial cycle—a stark contrast to the 76% retention after 20 cycles at 25 °C in conventional liquid batteries. Our strategy, which considers the principles of thermodynamics and kinetics, may open avenues for tackling the positive electrode|electrolyte interface issue in ASSLBs based on garnet-type SSEs.

Polyvinylidene fluoride gel‐polyethylene composite separator optimizing the interface compatibility between the separator and the electrode

AbstractThe interface issue concerning lithium dendrite formation between the separator and electrode remains a significant impediment to the further advancement of lithium‐ion batteries (LIB). Due to the inadequate interface compatibility between the conventional polyolefin separator and the electrode, there is a propensity for lithium dendrite growth. In this work, the surface of the polyethylene (PE) separator is coated with polyvinylidene fluoride (PVDF) gel using a simple phase transformation method, resulting in the preparation of a composite separator consisting of PE and PVDF. The results demonstrate an enhanced interface compatibility following the introduction of the gel layer, with a polarization voltage as low as 0.14 V observed after 250 h of cycling. Additionally, the ionic conductivity of the PE/PVDF composite separator (1.77 mS cm−1) is enhanced, attributed to the incorporation of F functional group in PVDF gel, which could facilitate the formation of a rapid ion transport pathway through the interaction between F functional group and Li+. After the introduction of the gel layer, the discharge capacity of the battery after 250 cycles measures ~1.28 mAh, with a mere 27% decay in capacity. This study presents a novel concept for the design of composite separator in LIB.

Bioinspired 3D printed elastomer-hydrogel hybrid with robust interfacial bonding for flexible ionotronics

Hydrogels are widely used in flexible ionotronics due to their continuous conductive phase and good biocompatibility. However, their poor mechanical properties affect their stability and lifespan. It is a significant challenge to prepare hydrogels with both high conductivity and mechanical strength, as improving the mechanical properties often results in a tighter network, which reduces electrical conductivity. Human skin is composed of a stiff collagen fibril scaffold for resisting external damage, and a soft matrix that detect various stimuli through ion transport. Herein, inspired by the structure of human skin, a hydrogel composite with remarkable mechanical properties, high ionic conductivity, and self-healing property is prepared. The composite structure with 3D printed elastomeric skeleton and hydrogel matrix, addresses both the contradiction between the ionic conductivity and mechanical properties of hydrogels, as well as the difficulty of realizing complex macrostructures of the skeleton. The issue of weak interface in composites is resolved by creating interfacial covalent bonds. The composite’s self-healing property, combined with a robust interface, ensure the stability and longevity of the composite when used as flexible sensors. This novel approach of creating robust interface is also employed in the encapsulation of hydrogels and the fabrication of flexible microcircuits.

Electrochemical Separations for Sustainability

This special issue of Interface comprises three articles that articulate the importance of electrochemical separations for sustainability. The articles emphasize electrochemical separations for industrial applications, such as gas purification (e.g., CO2 concentration, hydrogen purification, and ammonia compression), critical minerals refining, and nutrient and organic acid recovery. Electrochemical separations are a powerful tool for securing critical minerals and materials for the growing electrification of energy production and transmission while being more environmentally friendly (e.g., using renewable electrons and less solvent). For nutrient recovery, it is meaningful to capture and recycle phosphate from waste streams, as we are diminishing our phosphorus rock reserves. Plus, the energy intensive Haber-Bosch process contributes significantly to CO2 emissions. Recovering nitrate from wastewater and transforming nitrate back into ammonia can reduce the need for virgin ammonia from the Haber-Bosch process and the CO2 footprint for manufacturing fertilizers. Although water purification is an important sustainability topic in which electrochemical processes play an important role, water desalination by electrodialysis and other electrochemical platforms is not the focus of the articles in this issue due to the maturity of this technology.

Overview: Multifunctional Sensors for Smart Agriculture

Introduction to the Special Issue of Interface on Sensors for Smart Agriculture and Beyond

Multifunctional Acetamide Additive Combined with LiNO3 Co-Assists Low-Concentration Electrolyte Interfacial Stability for Lithium Metal Batteries.

Lithium metal batteries (LMBs) are expected to upgrade their energy density to meet the growing battery market demand; however, intractable lithium dendrites and prominent electrode-electrolyte interface problems have been the stumbling block to their practical applications. Electrolytes play a crucial role in LMBs and are directly involved in the establishment of the electrode-electrolyte interface. In particular, low-concentration electrolytes (LCEs) can significantly save electrolyte costs, but the interface issue is more noteworthy. Here, multifunctional acetamide (N-methyl-N-(trimethylsilyl)-trifluoroacetamide, MTA) and lithium nitrate (LiNO3) additives were introduced together to enhance the performance of LMBs in LCEs. The MTA additive effectively removes the trace water and corrosive HF from the electrolyte, thus suppressing lithium salt decomposition and enhancing the stability of LCEs. Moreover, the MTA additive can construct an inorganic-rich interphase layer on the cathode/anode surface to protect the electrode. Especially, MTA can cooperate with LiNO3 additive to suppress lithium dendrites and reduce interfacial impedance, thus effectively enhancing lithium metal anode stability. Benefiting from the introduction of MTA and LiNO3 additives in the LCEs, the Li||NMC811 metal battery still has a capacity of 110 mA h g-1 after 500 cycles at room temperature, while the reference batteries have failed. The rate capacity and high temperature (50 °C) performance of the Li||NCM811 batteries have also been significantly improved. Significantly, this research explores a cost-effective method of using multifunctional additives to enhance LMBs' stability in LCEs.

Quantum Dot Bridges Enabling Highly Efficient Carbon‐Based Hole Transport Material‐Free Perovskite Solar Cells

The realization of improved charge transport with suppressed recombination at the interface of perovskite and carbon electrode is the main key for remarkably increasing the power conversion efficiency of carbon‐based hole transport material (HTM)‐free perovskite solar cells (PSCs). Herein, a strategy that builds a perovskite quantum dot (PQD) interlayer is demonstrated, for the first time, to bridge the perovskite absorber and carbon electrode for solving the interface issue in HTM‐free PSCs. It is found that the introduced PQD interlayer concurrently functions as a morphology changer, a defect passivator, and a photogenerated hole extractor. Compared with the pristine perovskite film, the PQD‐modified perovskite absorber shows increased contact area and high compatibility with carbon electrode, prolonged carrier lifetime, deduced defect density as well as suppressed recombination. These positive effects, combined with a heterostructure created by perovskite bulks and PQDs facilitating hole transport at the interface, enable an improvement in device efficiency from 16.71% to 17.93%.

Special Issue of Interface on Commercialization of Electrochemistry and Material Science Technologies

Introduction to the Special Issue on on Commercialization of Electrochemistry and Material Science Technologies

SECURING CENTRALIZED SDN CONTROL WITH DISTRIBUTED BLOCKCHAIN TECHNOLOGY

Software Defined Networks (SDN) advocates segregation of network control logic, forwarding functions and management applications into different planes to achieve network programmability, automated and dynamic flow control in next generation networks. It promotes deployment of novel and augmented network management functions to have flexible, robust, scalable and cost-effective network deployments. All these features introduce new research challenges and require secure communication protocols among the segregated network planes. This manuscript focuses on the security issue of southbound interface which operates between the SDN control and data plane. We have highlighted the security threats associated with an unprotected southbound interface and the issues related with the existing TLS based security solution. A lightweight blockchain based decentralized security solution is proposed for southbound interface to secure the resources of logically centralized SDN controllers and distributed forwarding devices from opponents. The proposed mechanism can operate in multi-domain SDN deployment and can be used with wide range of network controllers and data plane devices. In addition to it, the proposed security solution is analyzed in terms of security features, communication and reauthentication overhead.

Special Issue of Interface on Neuromorphic Computing: An Introduction and State of the Field

The human brain integrates and processes information to perform complex cognitive tasks within approximately 20 watts of power. Today’s fastest supercomputer is unable to deliver the power requirements and the number of operations at the same energy levels. In the brain, the discrete and sparse events in time called spikes are used to process and encode the information. The energy efficiency of the brain is attributed to the sparsity of the spikes and event-driven communication between the neurons. Complex interconnections among the 1011 neurons and 1015 synapses in the human brain process the information, possibly encoded in the time, frequency, and phase of the spikes. Therefore, to emulate human cognition requires novel electronic devices and new algorithmic approaches. Brain-inspired computing, or neuromorphic computing, is an approach to build energy-efficient computing architectures and systems.

Superior tough, highly wear durable and self-lubricating epoxy composite co-enhanced by soft and hard nanomaterials

Despite many efforts are being undertaken to design high tribo-performance epoxy nanocomposite, it still remains a great challenge to comprehensively address the interface issue and poor mechanical strengths for real engineering requirements. This work reports a facile yet efficient strategy (synergism of soft and hard materials) to coordinate the interface-property relationship. Herein, we composited graphene with molybdenum disulfide to fabricate rGO-MoS2 interlayered nanostructure as hard solid lubricant, as the hyperbranched polysiloxane with unique flexible SiOC backbone was synthesized via facile polymerization as soft component within epoxy network. These two nanomaterials can be well used to construct EP composite for easy processing, and their merits regarding lubricity and toughening are well exerted, especially the interface could be improved without surface treatment. The optimized material with superior impact strength (23.5 ∼ 37.4 kJ·m−2), low friction coefficient (0.42 ∼ 0.16) and volume wear rate (70.6 % reduction) was obtained with respect to previous counterparts. Interestingly, TEM of ultra-thin resin slice found that hyperbranched polysiloxane could affect the distribution and nanostructured interface of graphene/MoS2, encouraging a facile and low-cost approach towards surface engineering of high-performance polymer composite. Besides, the tribo-mechanism and nano-reinforced mechanism were investigated and discussed in detail. In light of the compelling effects, this work paves an effective way toward the designs of high-performance polymer tribo-materials for real engineering uses.

Measurement of 64 organic thin-film transistors in an array test structure using a relay-switch board for efficient evaluation of long-term reliability

We propose an efficient array measurement test structure to measure many devices and to obtain statistical characteristics of organic thin-film-transistors (OTFT) for long-term reliability evaluation of new devices under development in laboratories and those that cannot achieve sufficient yield. We propose to adopt different devices from the device under test for the array control circuit. We implemented a separate control circuit as a dedicated relay-switch board without device consolidation. This relay-switch board can also apply voltage stress to any number of devices under test for negative bias temperature instability evaluation. The interface issue between the chip and board is resolved with a flexible flat cable and an anisotropic conductive film. The proposed measurement system successfully measured the OTFT arrays in (sweep time of source measure unit) × (number of OTFTs) period, and only requires 84 min for 64 nOTFTs (n-type OTFT) (552 points/device), which corresponds to 1.3 min/device in the experiment.

Practical semiconductor physics perspective of materials photoelectrochemistry

Large-scale production of H2 from renewable energy (solar) and renewable feed (water) is an important aspirational goal of the scientific enterprise. Implementation of solar-H2 via a device that integrates electrocatalysis and light absorption has been a rich source of physical electrochemistry but has not resulted in technology despite five decades of exploration. Semiconductor photoelectrochemistry is not only at the material interface of semiconductors and electrolyte, but is also at the interface of scientific practices of different communities. This review aims to provide a succinct overview of concepts emphasizing the coupled nature of physicochemical events, the critical need for stability at the interface and most challenging issue of directing electrons and holes to the surface via internal electric field. Finally, pointers to bring together the productive practices of the semiconductor and electrochemical community are provided.

From the President: Sustainable Solutions to Global Challenges Require Science and Innovation

Expanding on my earlier statement in the summer 2022 issue of Interface, I wish to share my views with you on the pressing challenges regarding sustainable energy and the environment. I will take an entirely global perspective in viewing these complex and difficult issues, irrespective of local or regional energy practices and trends that can mislead to tunnel vision.

Highly stretchable and strong poly (vinyl alcohol)-based hydrogel for reprogrammable actuator applications

Hydrogel is considered as a suitable choice for fabrication of actuators because of its similarity to biological tissues and multi-stimuli responsiveness. However, it is necessary to address the limit resulted from the traditional bilayer structure that leads to interface issue or permanent gradient structure that leads to unchangeable deformation mode. Herein, a highly-stretchable and reprogrammable PVA-based hydrogel actuator is reported. The actuator was fabricated through a freezing-thawing treatment of the blend of PVA, mono (9-anthracene methyl) succinate grafted PVA (PVA-SA-AN), tannic acid (TA) and cetyltrimethyl-ammonium bromide (CTAB) followed with UV irradiation. According to the scheme, PVA forms the hydrogel substrate and helps disperse the hydrophobic PVA-SA-AN into the hydrogel. TA forms hydrogen bonds with PVA and PVA-SA-AN, providing enhancement to the mechanical properties of the hydrogel. CTAB further disperses the anthracene groups so that the UV-induced reversible dimerization/cleavage can endow the hydrogel with the function of water-driven actuation as well as reversible programmability. The improved mechanical properties and the reprogrammable actuation performance are demonstrated. We believe that the proposed design strategy can provide a facile and low-cost way to develop high-performance reprogrammable hydrogel actuators.

Bridging the Gap Between Researchers and Teachers: A Curricular Perspective

AbstractThis study investigated the researcher–teacher interface issue by exploring second language (L2) teachers’ experiences of being involved in a large instructed second language acquisition empirical study aimed at curricular changes. The study addressed two goals. First, by involving the entire teaching staff at all levels of the multisection language teaching program in the administration of the empirical study, it examined the interface at the individual and the professional level. Second, by involving the teachers in every aspect of the study, it investigated the interface at the curricular level. Participants were 27 L2 teachers of Spanish at a private research university in the United States comprising graduate students of all disciplines and full‐time and adjunct faculty. The interface data were obtained via a survey with questions related to teachers’ academic backgrounds, pedagogical beliefs, experiences with academic journals, beliefs regarding the present study, overall experience, and their involvement in the research project. Two teachers also participated in in‐depth personal reflections. The results showed that the active participation by the teachers raised their level of awareness of the researcher–teacher and research–curriculum interfaces and also increased their overall personal and professional development as informed teachers who employ theoretically driven and empirically supported activities in their lesson plans.

High-performance gel electrolyte for enhanced interface compatibility and lithium metal stability in high-voltage lithium battery

All-solid-state lithium batteries are still plagued by poor interface issue and difficult to achieve commercialization within a short time. Quasi-solid electrolyte has become an important development strategy to compromise liquid battery and all-solid-state battery. Herein, a high-performance gel electrolyte for enhanced interface compatibility and lithium metal stability in high-voltage lithium battery was provided via in-situ polymerization of 1, 3-dioxolane (DOL) and 1, 2-dimethoxyethane (DME) under initiation of LiPF6. By adjusting the DOL/DME ratio, the electrochemical behavior of the gel electrolyte was optimized. The gel electrolyte with DOL/DME ratio of 1:1 has a high ionic conductivity of 3.3 × 10−4 S cm−1 and a Li+ migration number of 0.68. Based on this gel electrolyte, the interface compatibility and lithium metal stability in high-voltage lithium battery were greatly enhanced, the Li-Li symmetric cell can be stably cycled over 700 h with no obvious polarization at a current density of 0.1 mA cm−2, the capacity retention rate of the high-voltage NCM622/Li battery reaches above 80 % after 150 cycles at 0.5 C and 25 ℃. This work provides a practical idea for the development of high-performance polymer electrolytes and facilitates their application in Li-metal batteries.

Exploring Interfaces Through Synchrotron Radiation Characterization Techniques: A Graphene Case

AbstractRecently, many breakthroughs have been made in graphene research, allowing scientists to explore and understand the material world from a two‐dimensional (2D) perspective. The interface issue of graphene is the most important, because all of its atoms are exposed to the interface for this atomically thin material. The 2D nature necessitates a sensitive and non‐destructive interface probe to detect the structure and properties. Synchrotron radiation (SR) characterization techniques, with the ultra‐high resolution and extremely wide energy range, have been utilized with increasing frequency to explore the challenging interface sciences. In this review, these interface characterization techniques based on SR and how they monitor the structure evolution of graphene in different interfaces such as graphene–substrate and graphene–graphene interface are first introduced. Graphene's layer number, interlayer spacing, and stacking order are governed by these interfaces, determining the final properties. Then, the property detection and modulation in different interfaces of graphene are also discussed. Finally, the current challenges and outlook on the future development for SR techniques to characterize graphene interface are presented.