A Liquid Metal Microdroplets Initialized Hemicellulose Composite for 3D Printing Anode Host in Zn-Ion Battery

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. Initially, we compare the distinct characteristics of various printing technologies, and subsequently emphatically expound the printable components of micro-batteries and general approaches to prepare printable inks. After that, we focus on the outstanding role played by 3D printing design in the device architecture, battery configuration, performance improvement, and system integration. Finally, the future challenges and perspectives concerning high-performance 3D-printed micro-batteries are adequately highlighted and discussed. This comprehensive discussion aims at providing a blueprint for the design and construction of next-generation 3D-printed micro-batteries.

Green and Low-Cost Alkali-Polyphenol Synergetic Self-Catalysis System Access to Fast Gelation of Self-Healable and Self-Adhesive Conductive Hydrogels for Self-Powered Triboelectric Nanogenerators

Biomass-based hydrogels have attracted great attention in flexible and sustainable self-powered power sources but struggled to fabricate in a green, high-efficiency, and low-cost manner. Herein, a novel and facile alkali-polyphenol synergetic self-catalysis system is originally employed for the fast gelation of self-healable and self-adhesive lignin-based conductive hydrogels, which can be regarded as hydrogel electrodes of flexible triboelectric nanogenerators (TENGs). This synergy self-catalytic system comprises aqueous alkali and polyphenol-containing lignin, in which alkali-activated ammonium persulfate (APS) significantly accelerates the generation of radicals and initiates the polymerization of monomers, while polyphenol acts as a stabilizer to avoid bursting polymerization from inherent radical scavenging ability. Furthermore, multiple hydrogen bonds between lignin biopolymers and polyacrylamide (PAM) chains impart lignin-based hydrogels with exceptional adhesiveness and self-healing properties. Intriguingly, the alkaline conditions not only contribute to the solubility of lignin but also impart superior ionic conductivity of lignin-based hydrogel that is applicable to flexible TENG in self-powered energy-saving stair light strips, which holds great promise for industrial applications of soft electronics.

Current significance and future perspective of 3D-printed bio-based polymers for applications in energy conversion and storage system

The increasing global population has led to a surge in energy demand and the production of environmentally harmful products, highlighting the urgent need for renewable and clean energy sources. In this context, sustainable and eco-friendly energy production strategies have been explored to mitigate the adverse effects of fossil fuel consumption to the environment. Additionally, efficient energy storage devices with a long lifespan are also crucial. Tailoring the components of energy conversion and storage devices can improve overall performance. Three-dimensional (3D) printing provides the flexibility to create and optimize geometrical structure in order to obtain preferable features to elevate energy conversion yield and storage capacitance. It also serves the potential for rapid and cost-efficient manufacturing. Besides that, bio-based polymers with potential mechanical and rheological properties have been exploited as material feedstocks for 3D printing. The use of these polymers promoted carbon neutrality and environmentally benign processes. In this perspective, this review provides an overview of various 3D printing techniques and processing parameters for bio-based polymers applicable for energy-relevant applications. It also explores the advances and current significance on the integration of 3D-printed bio-based polymers in several energy conversion and storage components from the recently published studies. Finally, the future perspective is elaborated for the development of bio-based polymers via 3D printing techniques as powerful tools for clean energy supplies towards the sustainable development goals (SDGs) with respect to environmental protection and green energy conversion.

Liquid Metal-Based Stable and Stretchable Zn-Ion Battery for Electronic Textiles

Electronic textiles harmoniously interact with the human body and the surrounding environment, offering tremendous interest in smart wearable electronics. However, their wide application faces challenges due to the lack of stable and stretchable power electrodes/devices with multifunctional design. Herein, an intrinsically stretchable liquid metal-based fibrous anode for a stable Zn-ion battery (ZIB) is reported. Benefiting from the liquid feature and superior deformability of the liquid metal, optimized Zn ion concentration distribution and Zn (002) deposition behavior are observed, which result in dendrite-free performance even under stretching. With a strain of 50%, the ZIB maintains a high capacity of 139.8 mAh cm-3 (corresponding to 83.0% of the initial value) after 300 cycles, outperforming bare Zn fiber-based ZIB. The fibrous ZIB seamlessly integrates with the sensor, Joule heater, and wirelessly charging device, which provides a stable power supply for human signal monitoring and personal thermal management, holding promise for the application of wearable multifunctional electronic textiles.

Three-Dimensional Printing of Multifunctional Composites: Fabrication, Applications, and Biodegradability Assessment

Additive manufacturing, with its wide range of printable materials, and ability to minimize material usage, reduce labor costs, and minimize waste, has sparked a growing enthusiasm among researchers for the production of advanced multifunctional composites. This review evaluates recent reports on polymer composites used in 3D printing, and their printing techniques, with special emphasis on composites containing different types of additives (inorganic and biomass-derived) that support the structure of the prints. Possible applications for additive 3D printing have also been identified. The biodegradation potential of polymeric biocomposites was analyzed and possible pathways for testing in different environments (aqueous, soil, and compost) were identified, including different methods for evaluating the degree of degradation of samples. Guidelines for future research to ensure environmental safety were also identified.

Direct Ink Writing 3D Printing for High-Performance Electrochemical Energy Storage Devices: A Minireview

Despite tremendous efforts that have been dedicated to high-performance electrochemical energy storage devices (EESDs), traditional electrode fabrication processes still face the daunting challenge of limited energy/power density or compromised mechanical compliance. 3D thick electrodes can maximize the utilization of z-axis space to enhance the energy density of EESDs but still suffer from limitations in terms of poor mechanical stability and sluggish electron/ion transport. Direct ink writing (DIW), an eminent branch of 3D printing technology, has gained popularity in the manufacture of 3D electrodes with intricately designed architectures and rationally regulated porosity, promoting a triple boost in areal mass loading, ion diffusion kinetics, and mechanical flexibility. This focus review highlights the fundamentals of printable inks and typical configurations of 3D-printed devices. In particular, preparation strategies for high-performance and multifunctional 3D-printed EESDs are systemically discussed and classified according to performance evaluation metrics such as high areal energy density, high power density, high volumetric energy density, and mechanical flexibility. Challenges and prospects for the fabrication of high-performance 3D-printed EESDs are outlined, aiming to provide valuable insights into this thriving field.

Patterned Liquid-Metal-Enabled Universal Soft Electronics (PLUS-E) for Deformation Sensing on 3D Curved Surfaces

Liquid metals with metallic conductivity and infinitely deformable properties have tremendous potential in the field of conformal electronics. However, most processing methods of liquid metal electronics require sophisticated apparatus or custom masks, resulting in high processing costs and intricate preparation procedures. This study proposes a simple and rapid preparation method for patterned liquid-metal-enabled universal soft electronics (PLUS-E). The utilization of selective adhesion of the liquid metals on stretchable substrates and the adaptive toner mask enables rapid fabrication (<2 s/100 cm2), excellent stretchability (800% strain), and high forming accuracy (100 μm). Benefiting from the adaptive deformation of the substrate and toner mask, PLUS-E can be conformally applied to any shape of 3D surfaces. Besides, the stability of PLUS-E on 3D surfaces is improved by low-fluidity liquid metal composites. The finite element simulation is used to accurately forecast the deformation and resistance changes of the PLUS-E, and it provides guidance for device design and manufacturing. Finally, this method was utilized to develop various sensors for detecting human motion, catheter bending, and balloon expansion. All of them have obtained stable and reliable signal measurements, demonstrating the usefulness of PLUS-E in real-world applications.

Innovative Polymer Composites with Natural Fillers Produced by Additive Manufacturing (3D Printing)-A Literature Review

In recent years, plastics recycling has become one of the leading environmental and waste management issues. Along with the main advantage of plastics, which is undoubtedly their long life, the problem of managing their waste has arisen. Recycling is recognised as the preferred option for waste management, with the aim of reusing them to create new products using 3D printing. Additive manufacturing (AM) is an emerging and evolving rapid tooling technology. With 3D printing, it is possible to achieve lightweight structures with high dimensional accuracy and reduce manufacturing costs for non-standard geometries. Currently, 3D printing research is moving towards the production of materials not only of pure polymers but also their composites. Bioplastics, especially those that are biodegradable and compostable, have emerged as an alternative for human development. This article provides a brief overview of the possibilities of using thermoplastic waste materials through the application of 3D printing, creating innovative materials from recycled and naturally derived materials, i.e., biomass (natural reinforcing fibres) in 3D printing. The materials produced from them are ecological, widely available and cost-effective. Research activities related to the production of bio-based materials have gradually increased over the last two decades, with the aim of reducing environmental problems. This article summarises the efforts made by researchers to discover new innovative materials for 3D printing.

Biomass 3D Printing: Principles, Materials, Post-Processing and Applications

Under the background of green and low-carbon era, efficiently utilization of renewable biomass materials is one of the important choices to promote ecologically sustainable development. Accordingly, 3D printing is an advanced manufacturing technology with low energy consumption, high efficiency, and easy customization. Biomass 3D printing technology has attracted more and more attentions recently in materials area. This paper mainly reviewed six common 3D printing technologies for biomass additive manufacturing, including Fused Filament Fabrication (FFF), Direct Ink Writing (DIW), Stereo Lithography Appearance (SLA), Selective Laser Sintering (SLS), Laminated Object Manufacturing (LOM) and Liquid Deposition Molding (LDM). A systematic summary and detailed discussion were conducted on the printing principles, common materials, technical progress, post-processing and related applications of typical biomass 3D printing technologies. Expanding the availability of biomass resources, enriching the printing technology and promoting its application was proposed to be the main developing directions of biomass 3D printing in the future. It is believed that the combination of abundant biomass feedstocks and advanced 3D printing technology will provide a green, low-carbon and efficient way for the sustainable development of materials manufacturing industry.