3D Printing for Energy Storage Devices: Advances, Challenges, and Future Directions.

3D printing (3DP) has emerged as a transformative technology for the fabrication of electrochemical energy storage devices (EESDs), offering unprecedented advantages in design freedom, shape conformality, and material versatility. Unlike previous reviews that narrowly focus on specific materials or device types, this review offers a comprehensive and integrative perspective on the role of 3DP across the full architecture of EESDs, including batteries, supercapacitors, and fuel cells. Recent advances are highlighted in ink formulation strategies tailored for electrochemical functionality, advanced printing techniques enabling microscale precision and structural complexity, and the integration of printed components into functional devices.

Enhancing Hydrophilicity of Thick Electrodes for High Energy Density Aqueous Batteries.

Thick electrodes can substantially enhance the overall energy density of batteries. However, insufficient wettability of aqueous electrolytes toward electrodes with conventional hydrophobic binders severely limits utilization of active materials with increasing the thickness of electrodes for aqueous batteries, resulting in battery performance deterioration with a reduced capacity. Here, we demonstrate that controlling the hydrophilicity of the thicker electrodes is critical to enhancing the overall energy density of batteries.

Synergistic Interactions of Different Electroactive Components for Superior Lithium Storage Performance.

The fusion of different electroactive components of lithium-ion batteries (LIBs) sometimes brings exceptional electrochemical properties. We herein report the reduced graphene-oxide (rGO)-coated ZnSnO@NiO nanofibers (ZSO@NiO@G NFs) formed by the synergistic fusion of three different electroactive components including ZnO, SnO, and NiO that exhibit exceptional electrochemical properties as negative electrodes for LIBs. The simple synthetic route comprised of electrospinning and calcination processes enables to form porous one-dimensional (1D) structured ZSO, which is the atomic combination between ZnO and SnO, exhibiting effective strain relaxation during battery operation.

Colorimetric Dye-Loaded Nanofiber Yarn: Eye-Readable and Weavable Gas Sensing Platform.

The colorimetric gas sensor offers an opportunity for the simple and rapid detection of toxic gaseous substances based on visually discernible changes in the color of the sensing material. In particular, the accurate detection of trace amounts of certain biomarkers in a patient's breath provides substantial clues regarding specific diseases, for example, hydrogen sulfide (HS) for halitosis and ammonia (NH) for kidney disorder. However, conventional colorimetric sensors often lack the sensitivity, selectivity, detection limit, and mass-productivity, impeding their commercialization.

Gallium Nitride Nanoparticles Embedded in a Carbon Nanofiber Anode for Ultralong-Cycle-Life Lithium-Ion Batteries.

Recently, gallium (Ga), one of the liquid metals (LMs), has been explored with special attention because of its liquid phase nature as a self-healing agent and Li storage characteristics. The current challenge that restricts the practical use of Ga is handling Ga easily without loss and understanding its reaction behavior in Li-ion batteries. One solution that helps to address the problem associated with liquid phases is to make solid phases such as gallium oxides and nitrides as starting materials for a stable conversion reaction.

Atomic-scale combination of germanium-zinc nanofibers for structural and electrochemical evolution.

Alloys are recently receiving considerable attention in the community of rechargeable batteries as possible alternatives to carbonaceous negative electrodes; however, challenges remain for the practical utilization of these materials. Herein, we report the synthesis of germanium-zinc alloy nanofibers through electrospinning and a subsequent calcination step. Evidenced by in situ transmission electron microscopy and electrochemical impedance spectroscopy characterizations, this one-dimensional design possesses unique structures.

High-Power Aqueous Zinc-Ion Batteries for Customized Electronic Devices.

Wireless electronic devices require small, rechargeable batteries that can be rapidly designed and fabricated in customized form factors for shape conformable integration. Here, we demonstrate an integrated design and manufacturing method for aqueous zinc-ion batteries composed of polyaniline (PANI)-coated carbon fiber (PANI/CF) cathodes, laser micromachined zinc (Zn) anodes, and porous separators that are packaged within three-dimensional printed geometries, including rectangular, cylindrical, H-, and ring-shapes. The PANI/CF cathode possesses high surface area and conductivity giving rise to high rate (∼600 C) performance.

Ultrastable Graphene-Encapsulated 3 nm Nanoparticles by In Situ Chemical Vapor Deposition.

Nanoscale materials offer enormous opportunities for catalysis, sensing, energy storage, and so on, along with their superior surface activity and extremely large surface area. Unfortunately, their strong reactivity causes severe degradation and oxidation even under ambient conditions and thereby deteriorates long-term usability. Here superlative stable graphene-encapsulated nanoparticles with a narrow diameter distribution prepared via in situ chemical vapor deposition (CVD) are presented.

Stress-Tolerant Nanoporous Germanium Nanofibers for Long Cycle Life Lithium Storage with High Structural Stability.

Nanowires (NWs) synthesized via chemical vapor deposition (CVD) have demonstrated significant improvement in lithium storage performance along with their outstanding accommodation of large volume changes during the charge/discharge process. Nevertheless, NW electrodes have been confined to the research level due to the lack of scalability and severe side reactions by their high surface area. Here, we present nanoporous Ge nanofibers (NPGeNFs) having moderate nanoporosity via a combination of simple electrospinning and a low-energetic zincothermic reduction reaction.

Feasible Defect Engineering by Employing Metal Organic Framework Templates into One-Dimensional Metal Oxides for Battery Applications.

Facile synthesis of rationally designed nanostructured electrode materials with high reversible capacity is highly critical to meet ever-increasing demands for lithium-ion batteries. In this work, we employed defect engineering by incorporating metal organic framework (MOF) templates into one-dimensional nanostructures by simple electrospinning and subsequent calcination. The introduction of Co-based zeolite imidazole frameworks (ZIF-67) resulted in abundant oxygen vacancies, which induce not only more active sites for Li storage but also enhanced electrical conductivity.

Brush-Like Cobalt Nitride Anchored Carbon Nanofiber Membrane: Current Collector-Catalyst Integrated Cathode for Long Cycle Li-O Batteries.

To achieve a high reversibility and long cycle life for lithium-oxygen (Li-O) batteries, the irreversible formation of LiO, inevitable side reactions, and poor charge transport at the cathode interfaces should be overcome. Here, we report a rational design of air cathode using a cobalt nitride (CoN) functionalized carbon nanofiber (CNF) membrane as current collector-catalyst integrated air cathode. Brush-like CoN nanorods are uniformly anchored on conductive electrospun CNF papers via hydrothermal growth of Co(OH)F nanorods followed by nitridation step.

Cu Microbelt Network Embedded in Colorless Polyimide Substrate: Flexible Heater Platform with High Optical Transparency and Superior Mechanical Stability.

Metal nanowires have been considered as essential components for flexible transparent conducting electrodes (TCEs) with high transparency and low sheet resistance. However, large surface roughness and high interwire junction resistance limit the practical use of metal wires as TCEs. Here, we report Cu microbelt network (Cu MBN) with coalescence junction and low surface roughness for next-generation flexible TCEs.

Direct Realization of Complete Conversion and Agglomeration Dynamics of SnO Nanoparticles in Liquid Electrolyte.

The conversion reaction is important in lithium-ion batteries because it governs the overall battery performance, such as initial Coulombic efficiency, capacity retention, and rate capability. Here, we have demonstrated in situ observation of the complete conversion reaction and agglomeration of nanoparticles (NPs) upon lithiation by using graphene liquid cell transmission electron microscopy. The observation reveals that the Sn NPs are nucleated from the surface of SnO, followed by merging with each other.

Rational Design of 1-D CoO Nanofibers@Low content Graphene Composite Anode for High Performance Li-Ion Batteries.

Cobalt oxide that has high energy density, is the next-generation candidate as the anode material for LIBs. However, the practical use of CoO as anode material has been hindered by limitations, especially, low electrical conductivity and pulverization from large volume change upon cycling. These features lead to hindrance to its electrochemical properties for lithium-ion batteries.

Formation of a Surficial Bifunctional Nanolayer on Nb O for Ultrastable Electrodes for Lithium-Ion Battery.

Safe and long cycle life electrode materials for lithium-ion batteries are significantly important to meet the increasing demands of rechargeable batteries. Niobium pentoxide (Nb O ) is one of the highly promising candidates for stable electrodes due to its safety and minimal volume expansion. Nevertheless, pulverization and low conductivity of Nb O have remained as inherent challenges for its practical use as viable electrodes.

A High-Capacity and Long-Cycle-Life Lithium-Ion Battery Anode Architecture: Silver Nanoparticle-Decorated SnO/NiO Nanotubes.

The combination of high-capacity and long-term cyclability has always been regarded as the first priority for next generation anode materials in lithium-ion batteries (LIBs). To meet these requirements, the Ag nanoparticle decorated mesoporous SnO/NiO nanotube (m-SNT) anodes were synthesized via an electrospinning process, followed by fast ramping rate calcination and subsequent chemical reduction in this work. The one-dimensional porous hollow structure effectively alleviates a large volume expansion during cycling as well as provides a short lithium-ion duffusion length.

Dimensional Effects of MoS Nanoplates Embedded in Carbon Nanofibers for Bifunctional Li and Na Insertion and Conversion Reactions.

Controlling structural and morphological features of molybdenum disulfide (MoS) nanoplates determines anode reaction performance for Li-ion and Na-ion batteries. In this work, we investigate dimensional effects of MoS nanoplates randomly embedded in twisted mesoporous carbon nanofibers (MoS@MCNFs) on Li and Na storage properties. Considering dimensions of the MoS nanoplates (e.

A facile route for growth of CNTs on Si@hard carbon for conductive agent incorporating anodes for lithium-ion batteries.

Conductive agent incorporating Si anodes consisting of directly grown carbon nanotubes on hard carbon encapsulating Si nanoparticles were prepared by a one-pot chemical vapour deposition process. Owing to this fabulous structure, Si-based anodes exhibit excellent cycle retention and rate capability with a high-mass-loading of 3.5 mg cm(-2).

Multifunctional molecular design as an efficient polymeric binder for silicon anodes in lithium-ion batteries.

This work demonstrates the design, synthesis, characterization, and study of the electrochemical performance of a novel binder for silicon (Si) anodes in lithium-ion batteries (LIBs). Polymeric binders with three different functional groups, namely, carboxylic acid (COOH), carboxylate (COO(-)), and hydroxyl (OH), in a single polymer backbone have been synthesized and characterized via (1)H NMR and FTIR spectroscopies. A systematic study that involved varying the ratio of the functional groups indicated that a material with an acid-to-alcohol molar ratio of 60:40 showed promise as an efficient binder with an initial columbic efficiency of 89%.

Novel design of ultra-fast Si anodes for Li-ion batteries: crystalline Si@amorphous Si encapsulating hard carbon.

Nanocrystalline Si (c-Si) dispersed in amorphous Si (a-Si) encapsulating hard carbon (HC) has been synthesized as an anode material for fast chargeable lithium-ion batteries. The HC derived from natural polysaccharide was coated by a thin a-Si layer through chemical vapour deposition (CVD) using silane (SiH₄) as a precursor gas. The HC@c-Si@a-Si anodes showed an excellent cycle retention of 97.