Designing a Schottky Barrier-Free Interface for a Highly Conductive Anode in Proton Exchange Membrane Water Electrolysis.

Iridium, the most widely used anode catalyst in proton exchange membrane water electrolysis (PEMWE), must be used minimally due to its high price and limited supply. However, reducing iridium loading poses challenges due to abnormally large anode polarization. Herein, we present an anode catalyst layer (CL) based on a one-dimensional iridium nanofiber that enables a high current density operation of 3 A cm at 1.

High-Entropy Polymer Electrolytes Derived from Multivalent Polymeric Ligands for Solid-State Lithium Metal Batteries with Accelerated Li Transport.

Solid-state polymer-based electrolytes (SSPEs) exhibit great possibilities in realizing high-energy-density solid-state lithium metal batteries (SSLMBs). However, current SSPEs suffer from low ionic conductivity and unsatisfactory interfacial compatibility with metallic Li because of the high crystallinity of polymers and sluggish Li movement in SSPEs. Herein, differing from common strategies of copolymerization, a new strategy of constructing a high-entropy SSPE from multivariant polymeric ligands is proposed.

Potential-Dependent Ionomer Rearrangement on the Pt Surface in Polymer Electrolyte Membrane Fuel Cells.

The interface between the catalyst and the ionomer in the catalyst layer of polymer electrolyte membrane fuel cells (PEMFCs) has been a subject of keen interest, but its effect on durability has not been fully understood due to the complexity of the catalyst layer structure. Herein, we utilize a Pt nanoparticle (NP) array electrode fabricated using a block copolymer template as the platform for a focused investigation of the interfacial change between the Nafion thin film and the Pt NP under a constant potential. A set of analyses for the electrodes treated with various potentials reveals that the Nafion thin film becomes densely packed at the intermediate potentials (0.

Implementation of Field-Programmable Gate Array Platform for Object Classification Tasks Using Spike-Based Backpropagated Deep Convolutional Spiking Neural Networks.

This paper investigates the performance of deep convolutional spiking neural networks (DCSNNs) trained using spike-based backpropagation techniques. Specifically, the study examined temporal spike sequence learning via backpropagation (TSSL-BP) and surrogate gradient descent via backpropagation (SGD-BP) as effective techniques for training DCSNNs on the field programmable gate array (FPGA) platform for object classification tasks. The primary objective of this experimental study was twofold: (i) to determine the most effective backpropagation technique, TSSL-BP or SGD-BP, for deeper spiking neural networks (SNNs) with convolution filters across various datasets; and (ii) to assess the feasibility of deploying DCSNNs trained using backpropagation techniques on low-power FPGA for inference, considering potential configuration adjustments and power requirements.

Weakly coordinated Li ion in single-ion-conductor-based composite enabling low electrolyte content Li-metal batteries.

The pulverization of lithium metal electrodes during cycling recently has been suppressed through various techniques, but the issue of irreversible consumption of the electrolyte remains a critical challenge, hindering the progress of energy-dense lithium metal batteries. Here, we design a single-ion-conductor-based composite layer on the lithium metal electrode, which significantly reduces the liquid electrolyte loss via adjusting the solvation environment of moving Li in the layer. A Li||NiMnCoO pouch cell with a thin lithium metal (N/P of 2.

Modulating Ionic Transport and Interface Chemistry via Surface-Modified Silica Carrier in Nano Colloid Electrolyte for Stable Cycling of Li-Metal Batteries.

Tailoring the Li microenvironment is crucial for achieving fast ionic transfer and a mechanically reinforced solid-electrolyte interphase (SEI), which administers the stable cycling of Li-metal batteries (LMBs). Apart from traditional salt/solvent compositional tuning, this study presents the simultaneous modulation of Li transport and SEI chemistry using a citric acid (CA)-modified silica-based colloidal electrolyte (C-SCE). CA-tethered silica (CA-SiO ) can render more active sites for attracting complex anions, leading to further dissociation of Li from the anions, resulting in a high Li transference number (≈0.

A Mesoporous Tungsten Oxynitride Nanofibers/Graphite Felt Composite Electrode with High Catalytic Activity for the Cathode in Zn-Br Flow Battery.

High electrochemical polarization during a redox reaction in the electrode of aqueous zinc-bromine flow batteries largely limits its practical implementation as an effective energy storage system. This study demonstrates a rationally-designed composite electrode that exhibits a lower electrochemical polarization by providing a higher number of catalytically-active sites for faster bromine reaction, compared to a conventional graphite felt cathode. The composite electrode is composed of electrically-conductive graphite felt (GF) and highly active mesoporous tungsten oxynitride nanofibers (mWONNFs) that are prepared by electrospinning and simple heat treatments.

Confronting Sulfur Electrode Passivation and Li Metal Electrode Degradation in Lithium-Sulfur Batteries Using Thiocyanate Anion.

Salt anions with a high donor number (DN) enable high sulfur utilization in lithium-sulfur (Li-S) batteries by inducing three-dimensional (3D) Li S growth. However, their insufficient compatibility with Li metal electrodes limits their cycling stability. Herein, a new class of salt anion, thiocyanate (SCN ), is presented, which features a Janus character of electron donor and acceptor.

A Zinc-Bromine Battery with Deep Eutectic Electrolytes.

A deep eutectic solvent (DES) is an ionic liquid-analog electrolyte, newly emerging due to its low cost, easy preparation, and tunable properties. Herein, a zinc-bromine battery (ZBB) with a Zn-halide-based DES electrolyte prepared by mixing ZnBr , ZnCl , and a bromine-capturing agent is reported. The water-free DES electrolyte allows a closed-cell configuration for the ZBB owing to the prevention of Br evaporation and H evolution.

Regional Control of Multistimuli-Responsive Structural Color-Switching Surfaces by a Micropatterned DNA-Hydrogel Assembly.

Structural colors have advantages compared with chemical pigments or dyes, such as iridescence, tunability, and unfading. Many studies have focused on developing the ability to switch ON/OFF the structural color; however, they often suffer from a simple and single stimulus, remaining structural colors, and target selectivity. Herein, we present regionally controlled multistimuli-responsive structural color switching surfaces.

Modulation of Solvation Structure and Electrode Work Function by an Ultrathin Layer of Polymer of Intrinsic Microporosity in Zinc Ion Batteries.

Zinc ion batteries are promising candidates for large-scale energy storage systems. However, they suffer from the critical problems of insufficient cycling stability due to internal short-circuiting by zinc dendrites and zinc metal orphaning. In this work, a polymer of intrinsic microporosity (PIM-1) is reported as an ion regulating layer and an interface modulator, which promotes a uniform Zn plating and stripping process.

Hierarchical Wrinkle-Structured Catalyst Layer/Membrane Interface for Ultralow Pt-Loading Polymer Electrolyte Membrane Fuel Cells (PEMFCs).

The optimal architecture of three-dimensional (3D) interface between a polymer electrolyte membrane (PEM) and catalyst layer (CL) is one of the most important issues to improve PEM fuel cells' (PEMFCs) performance. Here, we report the fabrication of hierarchical wrinkled PEM/CL interface over a large area. We fabricated the hierarchical wrinkles on a multiscale from nanometers to micrometers by bottom-up-based facile, scalable, and simple method.

An electron-deficient carbon current collector for anode-free Li-metal batteries.

The long-term cycling of anode-free Li-metal cells (i.e., cells where the negative electrode is in situ formed by electrodeposition on an electronically conductive matrix of lithium sourced from the positive electrode) using a liquid electrolyte is affected by the formation of an inhomogeneous solid electrolyte interphase (SEI) on the current collector and irregular Li deposition.

Light-Designed Shark Skin-Mimetic Surfaces.

Sharks, marine creatures that swim fast and have an antifouling ability, possess dermal denticle structures of micrometer-size. Because the riblet geometries on the denticles reduce the shear stress by inducing the slip of fluid parallel to the stream-wise direction, shark skin has the distinguished features of low drag and antifouling. Although much attention has been given to low-drag surfaces inspired from shark skin, it remains an important challenge to accurately mimic denticle structures in the micrometer scale and to finely control their structural features.

Electrokinetic-Driven Fast Ion Delivery for Reversible Aqueous Zinc Metal Batteries with High Capacity.

Aqueous zinc (Zn) metal batteries (ZMBs) are considered a promising candidate for grid-scale energy storage due to their freedom from fire hazards. However, a limited reversibility of Zn metal electrode caused by dendritic Zn growth has hindered the advent of high-capacity Zn metal batteries (>4 mAh cm ). Herein, it is reported that fast electrokinetic Zn-ion transport extremely improves the Zn metal reversibility.

Lithium Dendrite Suppression with a Silica Nanoparticle-Dispersed Colloidal Electrolyte.

Developing a safe and long-lasting lithium (Li) metal battery is crucial for high-energy applications. However, its poor cycling stability due to Li dendrite formation and excessive Li pulverization is the major hurdle for its practical applications. Here, we present a silica (SiO) nanoparticle-dispersed colloidal electrolyte (NDCE) and its design principle for suppressing Li dendrite formation.

Light-induced surface patterning of alumina.

Micro/nano-patterned alumina surfaces are important in a variety fields such as chemical/biotechnology, surface science, and microelectro-mechanical systems. However, for patterning alumina surfaces, it still remains a challenge to have a lithographic tool that has large flexibility in design layouts, structural reconfigurability, and a simple fabrication process. In this work, a new alumina-patterning platform that uses a photo-reconfigurable azobenzene-alumina composite as an imprinting material is presented.

An Energy-Quality Scalable STDP Based Sparse Coding Processor With On-Chip Learning Capability.

Two main bottlenecks encountered when implementing energy-efficient spike-timing-dependent plasticity (STDP) based sparse coding, are the complex computation of winner-take-all (WTA) operation and repetitive neuronal operations in the time domain processing. In this article, we present an energy-efficient STDP based sparse coding processor. The low-cost hardware is based on the algorithmic reduction techniques as following: First, the complex WTA operation is simplified based on the prediction of spike emitting neurons.

Programmable Fabrication of Submicrometer Bent Pillar Structures Enabled by a Photoreconfigurable Azopolymer.

Anisotropic small structures found throughout living nature have unique functionalities as seen by Gecko lizards. Here, we present a simple yet programmable method for fabricating anisotropic, submicrometer-sized bent pillar structures using photoreconfiguration of an azopolymer. A slant irradiation of a p-polarized light on the pillar structure of an azopolymer simply results in a bent pillar structure.

High-Energy Efficiency Membraneless Flowless Zn-Br Battery: Utilizing the Electrochemical-Chemical Growth of Polybromides.

Aqueous Zn-Br batteries (ZBBs) offer promising next-generation high-density energy storage for energy storage systems, along with distinctive cost effectiveness particularly in membraneless and flowless (MLFL) form. Unfortunately, they generally suffer from uncontrolled diffusion of corrosive bromine components, which cause serious self-discharge and capacity fade. An MLFL-ZBB is presented that fundamentally tackles the problem of bromine crossover by converting bromine to the polybromide anion using protonated pyridinic nitrogen doped microporous carbon decorated on graphite felt (NGF).

Spike Counts Based Low Complexity SNN Architecture With Binary Synapse.

In this paper, we present an energy and area efficient spike neural network (SNN) processor based on novel spike counts based methods. For the low cost SNN design, we propose hardware-friendly complexity reduction techniques for both of learning and inferencing modes of operations. First, for the unsupervised learning process, we propose a spike counts based learning method.

Catalytic production of impurity-free V electrolyte for vanadium redox flow batteries.

The vanadium redox flow battery is considered one of the most promising candidates for use in large-scale energy storage systems. However, its commercialization has been hindered due to the high manufacturing cost of the vanadium electrolyte, which is currently prepared using a costly electrolysis method with limited productivity. In this work, we present a simpler method for chemical production of impurity-free V electrolyte by utilizing formic acid as a reducing agent and Pt/C as a catalyst.

Tuning Two Interfaces with Fluoroethylene Carbonate Electrolytes for High-Performance Li/LCO Batteries.

Various electrolytes have been reported to enhance the reversibility of Li-metal electrodes. However, for these electrolytes, concurrent and balanced control of Li-metal and positive electrode interfaces is a critical step toward fabrication of high-performance Li-metal batteries. Here, we report the tuning of Li-metal and lithium cobalt oxide (LCO) interfaces with fluoroethylene carbonate (FEC)-containing electrolytes to achieve high cycling stability of Li/LCO batteries.

High-Rate Cycling of Lithium-Metal Batteries Enabled by Dual-Salt Electrolyte-Assisted Micropatterned Interfaces.

We present a synergistic strategy to boost the cycling performance of Li-metal batteries. The strategy is based on the combined use of a micropattern (MP) on the surface of the Li-metal electrode and an advanced dual-salt electrolyte (DSE) system to more efficiently control undesired Li-metal deposition at higher current density (∼3 mA cm). The MP-Li electrode induces a spatially uniform current distribution to achieve dendrite-free Li-metal deposition beneath the surface layer formed by the DSE.

Rational Design of Highly Packed, Crack-Free Sulfur Electrodes by Scaffold-Supported Drying for Ultrahigh-Sulfur-Loaded Lithium-Sulfur Batteries.

Despite the notable progress in the development of rechargeable lithium-sulfur batteries over the last decade, achieving high performance with high-sulfur-loaded sulfur cathodes remains a key challenge on the path to the commercialization of practical lithium-sulfur batteries. This paper presents a novel method by which to fabricate a crack-free sulfur electrode with an ultrahigh sulfur loading (16 mg cm) and a high sulfur content (64%). By introducing a porous scaffold on the top of a cast of sulfur cathode slurry, the formation of cracks during the drying of the cast can be prevented due to the lower volume shrinkage of the skin.