Improved Capacitive Energy Storage Nanocomposites at High Temperature Utilizing Ultralow Loading of Bimetallic MOF

Improved capacitive energy storage performance in hybrid films with ultralow aminated molybdenum trioxide integration for high-temperature applications

Dielectric capacitors play a pivotal role in advanced high-power electrical and electronic applications, acting as essential components for electrical energy storage. The current trend towards miniaturization in electronic devices and power systems highlights the increasing demand for scalable, high-performance ultra-thin dielectric films with a high-temperature stability. While significant progress has been made in enhancing the discharged energy density (Ue) of dielectric polymers at elevated temperatures, such advancements have faced certain challenges. Herein, an innovative molecular engineering approach for the bonding of amine-functionalized molybdenum trioxide (A-MoO3) with the dianhydride monomer of polyetherimide (PEI) is presented, leading to a reduction in conduction loss and the substantial enhancement in storage energy density under high-temperature and high-field conditions. It is revealed that charge redistribution at the bonding sites induces a subtle variation in the potential energy, creating an in-built electric field between the PEI matrix and A-MoO3 based on density functional theory (DFT) analyses. The observed phenomenon leads to an increase in the electron barrier, effectively inhibiting the release of trapped electrons. Notably, at conditions of 200 °C and 100 Hz, the PEI/A-MoO3 hybrid film demonstrates a notable Ue at η > 90%, reaching up to 5.53 J cm-3, surpassing the performance of many current dielectric polymers and composites. Furthermore, the hybrid film's exceptional cycling durability, coupled with its ability to be fabricated into large-area, uniform-quality films, underscores its potential in the development of dielectric energy storage devices tailored for extreme environments.

Advances in Polymer Dielectrics with High Energy Storage Performance by Designing Electric Charge Trap Structures

Dielectric capacitors have been developed for nearly a century, and all-polymer film capacitors are currently the most popular. Much effort has been devoted to studying polymer dielectric capacitors and improving their capacitive performance, but their high conductivity and capacitance losses under high electric fields or elevated temperatures are still significant challenges. Although many review articles have reported various strategies to address these problems, to the best of current knowledge, no review article has summarized the recent progress in the high-energy storage performance of polymer-based dielectric films with electric charge trap structures. Therefore, this paper first reviews the charge trap characterization methods for polymeric dielectrics and discusses their strengths and weaknesses. The research progress on the design of charge trap structures in polymer dielectric films, including molecular chain optimization, organic doping, blending modification, inorganic doping, multilayered structures, and the mechanisms of the charge trap-induced enhancement of the capacitive performance of polymers are systematically reviewed. Finally, a summary and outlook on the fundamental theory of charge trap regulation, performance characterization, numerical calculations, and engineering applications are presented. This review provides a valuable reference for improving the insulation and energy storage performance of dielectric capacitive films.

Unifying and Suppressing Conduction Losses of Polymer Dielectrics for Superior High-Temperature Capacitive Energy Storage

Superior high-temperature capacitive performance of polymer dielectrics is critical for the modern film capacitor demanded in the harsh-environment electronic and electrical systems. Unfortunately, the capacitive performance degrades rapidly at elevated temperatures owing to the exponential growth of conduction loss. The conduction loss is mainly composed of electrode and bulk-limited conduction. Herein, the contribution of surface and bulk factors is unified to conduction loss, and the loss is thoroughly suppressed. The experimental results demonstrate that the polar oxygen-containing groups on the surface of polymer dielectrics can act as the charge trap sites to immobilize the injected charges from electrode, which can in turn establish a built-in field to weaken the external electric field and augment the injection barrier height. Wide bandgap aluminum oxide (Al2 O3 ) nanoparticle fillers can serve as deep traps to constrain the transport of injected or thermally activated charges in the bulk phase. From this, at 200 °C, the discharged energy density with a discharge-charge efficiency of 90% increases by 1058.06% from 0.31 J cm-3 for pristine polyetherimide to 3.59 J cm-3 for irradiated composite film. The principle of simultaneously inhibiting the electrode and bulk-limited conduction losses could be easily extended to other polymer dielectrics for high-temperature capacitive performance.

Bimetallic MOF-Derived Solar-Triggered Monolithic Adsorbent for Enhanced Atmospheric Water Harvesting

The development of economical, energy-saving, and efficient metal-organic framework (MOF)-based adsorbents for atmospheric water collection is highly imperative for the rapid advancement of renewable freshwater resource exploitation. Herein, a feasible one-step solvothermal formation strategy of bimetallic MOF (BMOF) is proposed and applied to construct a solar-triggered monolithic adsorbent for enhanced atmospheric water collection. Benefiting from the reorganization and adjustment of topology structure by Al atoms and Fe atoms, the resultant BMOF(3) consisting of Al-fumarate and MIL-88A has a higher specific surface area (1202.99 m2  g-1 ) and pore volume (0.51 cm3  g-1 ), thereby outperforming the parental MOFs and other potential MOFs in absorbing water. Expanding upon this finding, the solar-triggered monolithic adsorbent is further developed through a bottom-up assembly of polyaniline/chitosan layers and hybridized BMOF(3) skeletons on a glass fiber support. The resultant monolithic adsorbent exhibits superior sorption-desorption kinetics, leading to directional water transport and rapid solar-assisted vapor diffusion. As a proof-of-concept demonstration, an exquisite water harvester is constructed to emphasize a high water yield of 1.19 g g-1 per day of the designed monolithic adsorbent. Therefore, the design and validation of bimetallic MOF-derived solar-triggered adsorbent in this work are expected to provide a reference for the large-scale applications of MOF-based atmospheric water harvesting.