Flexible, ultrathin and integrated nanopaper supercapacitor based on cationic bacterial cellulose.

Cellulose composite nanopaper is extensively employed in flexible energy storage systems owing to their light weight, good flexibility and high specific surface area. Nevertheless, achieving flexible and ultrathin nanopaper supercapacitors with excellent electrochemical performance remains a challenge. Herein, surface cationization of bacterial cellulose (BC) nanofibers was conducted using 2,3-epoxypropyltrimethylammonium chloride (EPTMAC). Anion-doped polypyrrole (PPy) was incorporated onto the surface of the cationic bacterial cellulose (BCE) nanofibers by an interfacial electrostatic self-assembly process. The obtained PPy@BCE electrode exhibited excellent electrochemical performance, including an areal capacitance of 3988 mF cm-2 at 1.0 mA cm-2 and a capacitance retention of 97 % after 10,000 cycles. A laminated paper-forming strategy was adopted to design and fabricate all-in-one integrated flexible supercapacitors (IFSCs) using PPy@BCE nanopaper as electrodes and BC nanopaper as a separator. The IFSCs showed superior areal capacitance (3669 mF cm-2 at 1 mA cm-2), high energy density (193.7 µWh cm-2 at a power density of 827.3 µW cm-2), and outstanding mechanical flexibility (with no significant capacitance attenuation after repeatedly bending for 1000 times). The present strategy paves a way for the large-scale production of paper-based energy storage devices.

Unveiling Sustainable Potential: A Life Cycle Assessment of Plant-Fiber Composite Microcellular Foam Molded Automotive Components.

The development and utilization of new plant-fiber composite materials and microcellular foam molding processes for the manufacturing of automotive components are effective approaches when achieving the lightweight, low-carbon, and sustainable development of automobiles. However, current research in this field has mainly focused on component performance development and functional exploration, with a limited assessment of environmental performance, which fails to meet the requirements of the current green and sustainable development agenda. In this study, based on a life cycle assessment, the resource, and environmental impacts of plant-fiber composite material automotive components and microcellular foam molding processes were investigated. Furthermore, a combined approach to digital twinning and life cycle evaluation was proposed to conduct resource and environmental assessments and analysis. The research results indicate that under current technological conditions, resource and environmental issues associated with plant-fiber composite material automotive components are significantly higher than those of traditional material components, mainly due to differences in their early-stage processes and the consumption of electrical energy and chemical raw materials. It is noteworthy that electricity consumption is the largest influencing factor that causes environmental issues throughout the life cycle, especially accounting for more than 42% of indicators such as ozone depletion, fossil resource consumption, and carbon dioxide emissions. Additionally, the microcellular foam molding process can effectively reduce the environmental impact of products by approximately 15% and exhibits better overall environmental performance compared to chemical foaming. In future development, optimizing the forming process of plant-fiber composite materials, increasing the proportion of clean energy use, and promoting the adoption of microcellular foam injection molding processes could be crucial for the green and sustainable development of automotive components.

A Scalable Heat Pump Film with Zero Energy Consumption.

Radiative cooling is an effective technology with zero energy consumption to alleviate climate warming and combat the urban heat island effect. At present, researchers often use foam boxes to isolate non-radiant heat exchange between the cooler and the environment through experiments, so as to achieve maximum cooling power. In practice, however, there are challenges in setting up foam boxes on a large scale, resulting in coolers that can be cooled below ambient only under low convection conditions. Based on polymer materials and nano-zinc oxide (nano-ZnO, refractive index > 2, the peak equivalent spherical diameter 500 nm), the manufacturing process of heat pump film (HPF) was proposed. The HPF (4.1 mm thick) consists of polyethylene (PE) bubble film (heat transfer coefficient 0.04 W/m/K, 4 mm thick) and Ethylene-1-octene copolymer (POE) cured nano-ZnO (solar reflectance ≈94% at 0.075 mm thick). Covering with HPF, the object achieves 7.15 °C decreasing in normal natural environment and 3.68 °C even under certain circumstances with high surface convective heat transfer (56.9 W/m2/K). HPF has advantages of cooling the covered object, certain strength (1.45 Mpa), scalable manufacturing with low cost, hydrophobic characteristics (the water contact angle, 150.6°), and meeting the basic requirements of various application scenarios.

Easy Way to Achieve Self-Adaptive Cooling of Passive Radiative Materials.

Passive radiative cooling includes using the atmospheric window to emit heat energy to the cold outer space and hence reduce the temperature of objects on Earth. In most cases, radiative cooling is required in summer and suppressed in winter for thermal comfort. Recent radiative cooling materials cannot self-adjust cooling capacity according to season and environment, thus limiting their applications. In this study, we have designed a temperature-controlled phase change structure (TCPCS). The TCPCS benefits radiative coolers to adjust their cooling ability according to the ambient temperature. In the outdoor test, the TCPCS can help the cooler to turn off at low temperatures and turn on at high temperatures automatically; the coolers with and without TCPCS have maximal temperature differences of 9.7 and 19.6 °C, respectively, in a whole day. Furthermore, we have further improved and designed a V-shaped TCPCS that can simultaneously achieve the dual functions of cooling in summer and heating in winter. The TCPCS assembled here is a simple, feasible, and scalable structure for self-adaptive cooling.

TEMPO-oxidized bacterial cellulose nanofiber membranes as high-performance separators for lithium-ion batteries.

In this paper, 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized bacterial cellulose (TOBC) nanofiber membranes as separators of lithium-ion batteries were successfully prepared from a water dispersion of TOBC nanofibers via a vacuum filtration approach. The TOBC membranes had adequate porosity and desirable affinity with the liquid electrolyte and lithium electrode, giving rise to superior electrolyte uptake and small interfacial resistance. Among the TOBC nanofiber samples, the TOBC1.0 membrane exhibited the best properties, including high electrolyte uptake (339 %), superior electrochemical stability window (>6.0 V), outstanding ionic conductivity (13.45 mS cm-1) and small interfacial resistance (96 Ω). The half cells obtained using the TOBC1.0 membrane achieved a discharge capacity of 166 mA h g-1 (0.2 C), corresponding to 97.6 % of the theoretical value of LiFePO4 (170 mA h g-1), excellent cycle stability (with capacity retention of 94 % after 100 cycles) at 0.2 C and good C-rate performance. Thus, the TOBC nanofiber membranes could be considered as a promising high-performance separator used in lithium-ion batteries.

Thermoelectric Generator Using Space Cold Source.

Most of the renewable and sustainable natural energy is distributed uneven on the earth in time and space. Here we proposed a new kind of thermoelectric generator, which can use the temperature difference caused by passive cooling via the atmospheric window. This generator can continuously output electric energy anywhere 24 h a day independent of the existence of any natural or manmade energy resource. A test generator with two couples of n-p thermoelectric legs has been prepared. The created average temperature difference is 4.4 K and average voltage is 1.78 mV in a whole day. This design paves a path to the pollution-free and sustainable power generation which is not restricted by time and space and not consuming any existing energy resource.

A Combined In-Mold Decoration and Microcellular Injection Molding Method for Preparing Foamed Products with Improved Surface Appearance.

A combined in-mold decoration and microcellular injection molding (IMD/MIM) method by integrating in-mold decoration injection molding (IMD) with microcellular injection molding (MIM) was proposed in this paper. To verify the effectiveness of the IMD/MIM method, comparisons of in-mold decoration injection molding (IMD), conventional injection molding (CIM), IMD/MIM and microcellular injection molding (MIM) simulations and experiments were performed. The results show that compared with MIM, the film flattens the bubbles that have not been cooled and turned to the surface, thus improving the surface quality of the parts. The existence of the film results in an asymmetrical temperature distribution along the thickness of the sample, and the higher temperature on the film side leads the cell to move toward it, thus obtaining a cell-offset part. However, the mechanical properties of the IMD/MIM splines are degraded due to the presence of cells, while specific mechanical properties similar to their solid counterparts are maintained. Besides, the existence of the film reduces the heat transfer coefficient of the film side so that the sides of the part are cooled asymmetrically, causing warpage.