Vacancies Engineering in Molybdenum Boride MBene Nanosheets to Activate Room-Temperature Ferromagnetism.

The rapid development of low energy dissipation spintronic devices has stimulated the search for air-stable 2D nanomaterials possessing room-temperature ferromagnetism. Here the experimental realization of 2D MoB nanosheets is reported with intrinsic room-temperature ferromagnetic characteristics by vacancy engineering. These nanosheets are synthesized by etching the bulk MAB phase (MoY)AlB into MoB nanosheets in ZnCl molten salt.

The status and challenging perspectives of 3D-printed micro-batteries.

In the era of the Internet of Things and wearable electronics, 3D-printed micro-batteries with miniaturization, aesthetic diversity and high aspect ratio, have emerged as a recent innovation that solves the problems of limited design diversity, poor flexibility and low mass loading of materials associated with traditional power sources restricted by the slurry-casting method. Thus, a comprehensive understanding of the rational design of 3D-printed materials, inks, methods, configurations and systems is critical to optimize the electrochemical performance of customizable 3D-printed micro-batteries. In this review, we offer a key overview and systematic discussion on 3D-printed micro-batteries, emphasizing the close relationship between printable materials and printing technology, as well as the reasonable design of inks.

Metal telluride nanosheets by scalable solid lithiation and exfoliation.

Transition metal tellurides (TMTs) have been ideal materials for exploring exotic properties in condensed-matter physics, chemistry and materials science. Although TMT nanosheets have been produced by top-down exfoliation, their scale is below the gram level and requires a long processing time, restricting their effective application from laboratory to market. We report the fast and scalable synthesis of a wide variety of MTe (M = Nb, Mo, W, Ta, Ti) nanosheets by the solid lithiation of bulk MTe within 10 min and their subsequent hydrolysis within seconds.

Monolithically integrated micro-supercapacitors with high areal number density produced by surface adhesive-directed electrolyte assembly.

Accurately placing very small amounts of electrolyte on tiny micro-supercapacitors (MSCs) arrays in close proximity is a major challenge. This difficulty hinders the development of densely-compact monolithically integrated MSCs (MIMSCs). To overcome this grand challenge, we demonstrate a controllable electrolyte directed assembly strategy for precise isolation of densely-packed MSCs at micron scale, achieving scalable production of MIMSCs with ultrahigh areal number density and output voltage.

Hierarchically Structured NbO Microflowers with Enhanced Capacity and Fast-Charging Capability for Flexible Planar Sodium Ion Micro-Supercapacitors.

Highlights: Hierarchically structured NbO microflowers consiste of porous and ultrathin nanosheets. NbO microflowers exhibit enhanced capacity and rate performance boosting Na ion storage. Planar NIMSCs with charge and kinetics matching show superior areal capacitance and lifespan.

Monolithic integrated micro-supercapacitors with ultra-high systemic volumetric performance and areal output voltage.

Monolithic integrated micro-supercapacitors (MIMSCs) with high systemic performance and cell-number density are important for miniaturized electronics to empower the Internet of Things. However, fabrication of customizable MIMSCs in an extremely small space remains a huge challenge considering key factors such as materials selection, electrolyte confinement, microfabrication and device-performance uniformity. Here, we develop a universal and large-throughput microfabrication strategy to address all these issues by combining multistep lithographic patterning, spray printing of MXene microelectrodes and controllable 3D printing of gel electrolytes.

3D Printing Flexible Sodium-Ion Microbatteries with Ultrahigh Areal Capacity and Robust Rate Capability.

Rechargeable sodium-ion microbatteries (NIMBs) constructed using low-cost and abundant raw materials in planar configuration with both cathode and anode on the same substrate hold promise for powering coplanar microelectronics, but are hindered by the low areal capacity owing to the thin microelectrodes. Here, a prototype of planar and flexible 3D-printed NIMBs is demonstrated with 3D interconnected conductive thick microelectrodes for ultrahigh areal capacity and boosted rate capability. Rationally optimized 3D printable inks with appropriate viscosities and high conductivity allow the multilayer printing of NIMB microelectrodes reaching a very high thickness of ≈1200 µm while maintaining effective ion and electron-transfer pathways in them.

Kinetic regulation of MXene with water-in-LiCl electrolyte for high-voltage micro-supercapacitors.

MXenes are one of the key materials for micro-supercapacitors (MSCs), integrating miniaturized energy-storage components with microelectronics. However, the energy densities of MSCs are greatly hampered by MXenes' narrow working potential window (typically ≤0.6 V) in aqueous electrolytes.

Multifunctional Mesoporous Polyaniline/Graphene Nanosheets for Flexible Planar Integrated Microsystem of Zinc Ion Microbattery and Gas Sensor.

The prosperity of smart portable microdevices urgently requires an advanced integrated microsystem equipped with cost-effective safe microbatteries and ultra-stable sensitive sensors. However, the practical application of smart microdevices is limited by complex active materials with single function. Here, the two-dimensional (2D) mesoporous nanosheets of polyaniline decorated on graphene with large specific surface area of 141 m  g , ample active sites, comparable conductivity, and ordered mesopores of 18 nm for a new-type co-planar integrated microsystem of zinc ion microbattery and gas sensor are developed.

2.4 V ultrahigh-voltage aqueous MXene-based asymmetric micro-supercapacitors with high volumetric energy density toward a self-sufficient integrated microsystem.

Two-dimensional MXenes are key high-capacitance electrode materials for micro-supercapacitors (MSCs) catering to integrated microsystems. However, the narrow electrochemical voltage windows of conventional aqueous electrolytes (≤ 1.23 V) and symmetric MXene MSCs (typically ≤ 0.

Multi-Layer Printable Lithium Ion Micro-Batteries with Remarkable Areal Energy Density and Flexibility for Wearable Smart Electronics.

Pursuing high areal energy density and developing scalable fabrication strategies of micro-batteries are the key for the progressive printed microelectronics. Herein, the scalable fabrication of multi-layer printable lithium ion micro-batteries (LIMBs) with ultrahigh areal energy density and exceptional flexibility is reported, based on highly conductive and mechanically stable inks by fully incorporating the polyurethane binders in dibasic esters with high-conducting additives of graphene and carbon nanotubes into active materials to construct a cross-linked conductive network. Benefiting from relatively higher electrical conductivity (≈7000 mS cm ) and stably connected network of microelectrodes, the as-fabricated LIMBs by multi-layer printing display robust areal capacity of 398 µAh cm , and remarkable areal energy density of 695 μWh cm , which are much higher than most LIMBs reported.

Rapid Ion Transport Induced by the Enhanced Interaction in Composite Polymer Electrolyte for All-Solid-State Lithium-Metal Batteries.

High-quality solid electrolyte is the key to developing high-performance all-solid-state lithium-metal batteries (ASSLMBs). Herein, we report a thin composite polymer electrolyte (CPE) based on nanosized LiLaZrTaO (N-LLZTO) and the PVDF-HFP matrix through a simple film-casting method. N-LLZTO induces partial dehydrofluorination of the poly(vinylidene fluoride--hexafluoropropylene) (PVDF-HFP) matrix that activates the coordination of Li with PVDF-HFP and LLZTO due to Lewis acid-base interactions, which facilitates dissociation of lithium salt to increase the Li carrier density.

Multitasking MXene Inks Enable High-Performance Printable Microelectrochemical Energy Storage Devices for All-Flexible Self-Powered Integrated Systems.

The future of mankind holds great promise for things like the Internet of Things, personal health monitoring systems, and smart cities. To achieve this ambitious goal, it is imperative for electronics to be wearable, environmentally sustainable, and safe. However, large-scale manufacture of self-sufficient electronic systems by exploiting multifunctional materials still faces significant hurdles.

Three dimensional TiC MXene nanoribbon frameworks with uniform potassiophilic sites for the dendrite-free potassium metal anodes.

Potassium (K) metal batteries hold great promise as an advanced electrochemical energy storage system because of their high theoretical capacity and cost efficiency. However, the practical application of K metal anodes has been limited by their poor cycling life caused by dendrite growth and large volume changes during the plating/stripping process. Herein, three-dimensional (3D) alkalized TiC (a-TiC) MXene nanoribbon frameworks were demonstrated as advanced scaffolds for dendrite-free K metal anodes.

3D Flexible, Conductive, and Recyclable TiCT MXene-Melamine Foam for High-Areal-Capacity and Long-Lifetime Alkali-Metal Anode.

Alkali metals are ideal anodes for high-energy-density rechargeable batteries, while seriously hampered by limited cycle life and low areal capacities. To this end, rationally designed frameworks for dendrite-free and volume-changeless alkali-metal deposition at both high current densities and capacities are urgently required. Herein, a general 3D conductive TiCT MXene-melamine foam (MXene-MF) is demonstrated as an elastic scaffold for dendrite-free, high-areal-capacity alkali anodes (Li, Na, K).

Scalable fabrication of printed Zn//MnO planar micro-batteries with high volumetric energy density and exceptional safety.

The rapid development of printed and microscale electronics imminently requires compatible micro-batteries (MBs) with high performance, applicable scalability, and exceptional safety, but faces great challenges from the ever-reported stacked geometry. Herein the first printed planar prototype of aqueous-based, high-safety Zn//MnO MBs, with outstanding performance, aesthetic diversity, flexibility and modularization, is demonstrated, based on interdigital patterns of Zn ink as anode and MnO ink as cathode, with high-conducting graphene ink as a metal-free current collector, fabricated by an industrially scalable screen-printing technique. The planar separator-free Zn//MnO MBs, tested in neutral aqueous electrolyte, deliver a high volumetric capacity of 19.

All-Solid-State Planar Sodium-Ion Microcapacitors with Multidirectional Fast Ion Diffusion Pathways.

With the relentless development of smart and miniaturized electronics, the worldwide thirst for microscale electrochemical energy storage devices with form factors is launching a new era of competition. Herein, the first prototype planar sodium-ion microcapacitors (NIMCs) are constructed based on the interdigital microelectrodes of urchin-like sodium titanate as faradaic anode and nanoporous activated graphene as non-faradaic cathode along with high-voltage ionogel electrolyte on a single flexible substrate. By effectively coupling with battery-type anode and capacitor-type cathode, the resultant all-solid-state NIMCs working at 3.

The Road Towards Planar Microbatteries and Micro-Supercapacitors: From 2D to 3D Device Geometries.

The rapid development and further modularization of miniaturized and self-powered electronic systems have substantially stimulated the urgent demand for microscale electrochemical energy storage devices, e.g., microbatteries (MBs) and micro-supercapacitors (MSCs).

Electrochemically Scalable Production of Fluorine-Modified Graphene for Flexible and High-Energy Ionogel-Based Microsupercapacitors.

Scalable production of high-quality heteroatom-modified graphene is critical for microscale supercapacitors but remains a great challenge. Herein, we demonstrate a scalable, single-step electrochemical exfoliation of graphite into highly solution-processable fluorine-modified graphene (FG), achieved in an aqueous fluorine-containing neutral electrolyte, for flexible and high-energy-density ionogel-based microsupercapacitors (FG-MSCs). The electrochemically exfoliated FG nanosheets are characterized by atomic thinness, large lateral size (up to 12 μm), a high yield of >70% with ≤3 layers, and a fluorine doping of 3 at%, allowing for large-scale production of FG-MSCs.

All-MXene-Based Integrated Electrode Constructed by TiC Nanoribbon Framework Host and Nanosheet Interlayer for High-Energy-Density Li-S Batteries.

High-energy-density lithium-sulfur (Li-S) batteries hold promise for next-generation portable electronic devices, but are facing great challenges in rational construction of high-performance flexible electrodes and innovative cell configurations for actual applications. Here we demonstrated an all-MXene-based flexible and integrated sulfur cathode, enabled by three-dimensional alkalized TiC MXene nanoribbon (a-TiC MNR) frameworks as a S/polysulfides host (a-TiC-S) and two-dimensional delaminated TiC MXene (d-TiC) nanosheets as interlayer on a polypropylene (PP) separator, for high-energy and long-cycle Li-S batteries. Notably, an a-TiC MNR framework with open interconnected macropores and an exposed surface area guarantees high S loading and fast ionic diffusion for prompt lithiation/delithiation kinetics, and the 2D d-TiC MXene interlayer remarkably prevents the shuttle effect of lithium polysulfides via both chemical absorption and physical blocking.

2D transition metal carbide MXene as a robust biosensing platform for enzyme immobilization and ultrasensitive detection of phenol.

MXene-TiC, as a new class of two-dimensional (2D) transition metal carbides (or nitrides), has been synthesized by exfoliating pristine TiAlC phases with hydrofluoric acid. The SEM and XRD images show that the resultant MXene possesses a graphene-like 2D nanostructure. and the surface of MXene has been partially terminated with -OH, thus providing a favorable microenvironment for enzyme immobilization and retaining their bioactivity and stability.

Conductive Microporous Covalent Triazine-Based Framework for High-Performance Electrochemical Capacitive Energy Storage.

Nitrogen-enriched porous nanocarbon, graphene, and conductive polymers attract increasing attention for application in supercapacitors. However, electrode materials with a large specific surface area (SSA) and a high nitrogen doping concentration, which is needed for excellent supercapacitors, has not been achieved thus far. Herein, we developed a class of tetracyanoquinodimethane-derived conductive microporous covalent triazine-based frameworks (TCNQ-CTFs) with both high nitrogen content (>8 %) and large SSA (>3600 m  g ).

Graphene-Based Linear Tandem Micro-Supercapacitors with Metal-Free Current Collectors and High-Voltage Output.

Printable supercapacitors are regarded as a promising class of microscale power source, but are facing challenges derived from conventional sandwich-like geometry. Herein, the printable fabrication of new-type planar graphene-based linear tandem micro-supercapacitors (LTMSs) on diverse substrates with symmetric and asymmetric configuration, high-voltage output, tailored capacitance, and outstanding flexibility is demonstrated. The resulting graphene-based LTMSs consisting of 10 micro-supercapacitors (MSs) present efficient high-voltage output of 8.

One-Step Device Fabrication of Phosphorene and Graphene Interdigital Micro-Supercapacitors with High Energy Density.

Rational engineering and simplified fabrication of high-energy micro-supercapacitors (MSCs) using graphene and other 2D nanosheets are of great value for flexible and integrated electronics. Here we develop one-step mask-assisted simplified fabrication of high-energy MSCs (PG-MSCs) based on the interdigital hybrid electrode (PG) patterns of stacking high-quality phosphorene nanosheets and electrochemically exfoliated graphene in ionic liquid electrolyte. The hybrid PG films with interdigital patterns were directly manufactured by layer-by-layer deposition of phosphorene and graphene nanosheets with the assistance of a customized interdigital mask, and directly transferred onto a flexible substrate.

TiC MXene-Derived Sodium/Potassium Titanate Nanoribbons for High-Performance Sodium/Potassium Ion Batteries with Enhanced Capacities.

Sodium and potassium ion batteries hold promise for next-generation energy storage systems due to their rich abundance and low cost, but are facing great challenges in optimum electrode materials for actual applications. Here, ultrathin nanoribbons of sodium titanate (M-NTO, NaTiO) and potassium titanate (M-KTO, KTiO) were successfully synthesized by a simultaneous oxidation and alkalization process of TiC MXene. Benefiting from the suitable interlayer spacing (0.