A high-performance magneto-mechano-triboelectric nanogenerator (MMTEG) was demonstrated by introducing accelerated water-soluble nano-bullet modified nanostructures to convert a gentle magnetic field into electric energy for powering an indoor wireless positioning system. NaCl salt nanoparticles were accelerated by an aerosol deposition (AD) process to collide on a perfluoroalkoxy (PFA) film with a high kinetic energy for the formation of a complicated nanomorphology on the triboelectric active surface. Under an alternating current (AC) magnetic field of 7 Oe, the MMTEG generated an open-circuit peak-to-peak voltage (V_pp) and a short-circuit current of 708 V and 277 μA, respectively. The harvesting device also presented a maximum peak power of 21.8 mW as well as a continuous AC output power of 4.8 mW (4.8 mJ per second). A self-powered indoor IoT positioning system was constructed by integrating the MMTEG, a power managing circuit, a storage element, and an IoT Bluetooth beacon. The electric energy from the MMTEG device enabled continuous operation of a beacon device, and we successfully confirmed the accurate location of the installed wireless positioning system, subsequently resulting in transmission of our indoor position to the main monitoring computer. Lastly, the MMTEG generated an open-circuit V_pp and a short-circuit current of 330 V and 23 μA, respectively, near a 60 Hz power cable connected to home appliances, which were large enough to turn on 108 blue light emitting diodes (LEDs).

Materials offering high energy density are currently desired to meet the increasing demand for energy storage applications, such as pulsed power devices, electric vehicles, high-frequency inverters, and so on. Particularly, ceramic-based dielectric materials have received significant attention for energy storage capacitor applications due to their outstanding properties of high power density, fast charge–discharge capabilities, and excellent temperature stability relative to batteries, electrochemical capacitors, and dielectric polymers. In this paper, we present fundamental concepts for energy storage in dielectrics, key parameters, and influence factors to enhance the energy storage performance, and we also summarize the recent progress of dielectrics, such as bulk ceramics (linear dielectrics, ferroelectrics, relaxor ferroelectrics, and anti-ferroelectrics), ceramic films, and multilayer ceramic capacitors. In addition, various strategies, such as chemical modification, grain refinement/microstructure, defect engineering, phase, local structure, domain evolution, layer thickness, stability, and electrical homogeneity, are focused on the structure–property relationship on the multiscale, which has been thoroughly addressed. Moreover, this review addresses the challenges and opportunities for future dielectric materials in energy storage capacitor applications. Overall, this review provides readers with a deeper understanding of the chemical composition, physical properties, and energy storage performance in this field of energy storage ceramic materials.

Ceramic capacitors have received great attention for use in pulse power systems owing to their ultra-fast charge–discharge rate, good temperature stability, and excellent fatigue resistance. However, the low energy storage density and low breakdown strength (BDS) of ceramic capacitors limit the practical applications of energy storage technologies. In this work, we present a series of relaxor ferroelectric ceramics (1−x) [0.94 Bi_0.5Na_0.5TiO₃ –0.06BaTiO₃]– x Sr_0.7Bi_0.2TiO₃ (1-x BNT-BT- x SBT; x = 0, 0.20, 0.225, 0.25, 0.275 and 0.30) with improved energy storage performances by combining relaxor and antiferroelectric properties. XRD, Raman spectra, and SEM characterizations of BNT-BT-SBT ceramics revealed a rhombohedral–tetragonal phase, highly dynamic polar nanoregions, and a reduction in grain size with a homogeneous and dense microstructure, respectively. A high dielectric constant of 1654 at 1 kHz and low remnant polarization of 1.39 µC/cm² were obtained with the addition of SBT for x = 0.275; these are beneficial for improving energy storage performance. The diffuse phase transition of these ceramics displays relaxor behavior, which is improved with SBT and confirmed by modified the Curie–Weiss law. The combining relaxor and antiferroelectric properties with fine grain size by the incorporation of SBT enables an enhanced maximum polarization of a minimized P-E loop, leading to an improved BDS. As a result, a high recoverable energy density W_rec of 1.02 J/cm³ and a high energy efficiency η of 75.98% at 89 kV/cm were achieved for an optimum composition of 0.725 [0.94BNT-0.06BT]-0.275 SBT. These results demonstrate that BNT-based relaxor ferroelectric ceramics are good candidates for next-generation ceramic capacitors and offer a potential strategy for exploiting novel high-performance ceramic materials.

In this study, we demonstrated the nanostructuring of the ferroelectric (FE) phase of Pb(Zr_0.95Ti_0.05)O₃ (PZT-95/5) into a thick film with relaxor-like FE (RFE) characteristics. This transformation results in exceptionally high dielectric breakdown strength (E _DBS ) and energy storage density properties. The high kinetic energy from aerosol deposition transformed the bulk PZT-95/5 from a normal FE system into a RFE system by forming a nanostructured grain with nanodomains within a nonpolar matrix. This nanostructure enables easy domain switching, resulting in low remanent polarization. The resulting high density of grain boundaries due to nanograin formation and the nonpolar structure act as barriers to charge flow, resulting in high breakdown strength. Collectively, these effects resulted in a significantly enhanced E _DBS of 5.6 MV/cm and a maximum polarization of 80 µC/cm². These properties, evidenced by slim hysteresis loops, demonstrate that the prepared PZT-95/5 thick film is a superior capacitive material with a high recoverable energy density of 116 J/cm³. Furthermore, the film exhibited reliable fatigue endurance up to 10⁷ cycles and thermal stability from room temperature to 140^°C. The film also exhibited a peak power density of 35 MW/cm³ under a practical electric field of 0.45 MV/cm (180 V) and a fast discharging speed (τ _0.9) of 230 ns. These properties, in addition to the minimal fabrication steps and superior capacitive characteristics, demonstrate the strong potential of the prepared PZT-95/5 thick film for use in next-generation energy storage devices.

The global transition to sustainable energy solutions has increased demand for green energy sources, especially for miniature and wearable electronic devices. Scavenging ambient mechanical energy is a practical approach for powering low-energy devices independently. Piezoelectric energy harvesting is a fundamental approach in energy conversion technologies. Due to significant environmental and health risks, lead-based ceramics such as lead zirconate titanate were restricted, which pushed the search for alternative, environmentally friendly materials. This review emphasizes the critical importance of replacing hazardous lead-based materials with lead-free alternatives. Moreover, a comprehensive overview of the progress and implementation of lead-free piezoelectric materials in next-generation energy harvesting technologies, encompassing piezoelectric, triboelectric, magneto-mechano-electric, and hybrid systems. In addition, this review covers flexible and composite structures, with a focus on mechanical flexibility and long-term functional stability. These materials have been applied in biomedical implants, defense applications, wearable sensing devices, and remote monitoring systems. This review also outlines the critical steps to achieving an optimal balance among energy conversion efficiency, biocompatibility, and mechanical robustness. Recent advances and strategies for implementing biocompatible, lead-free energy-harvesting technologies enable the integration of green power sources into futuristic, sustainable, and secure electronic devices.

High-entropy ceramics (HECs) embrace compositional complexity and configurational entropy to reinvent the science of traditional ceramic design. They display high thermal, mechanical, electrical, and chemical resilience and, to achieve this incredible feat, incorporate four or more elements in near-equiatomic ratios to stabilize single-phase solid solutions. By beginning with the conceptual development of high-entropy alloys, the review critically examines the role of configurational entropy in overcoming phase separation. A comprehensive discussion on the implications of ionic radius mismatch, lattice distortion, and electronegativity changes on microstructure and the tuning of functional properties is presented. Analysis of various synthesis processes and their influence on grain size, densification, phase composition, and the resulting material properties is also discussed. The intricate details of fine-grain engineering and the role of entropy in homogenizing microstructure and mechanical properties, such as improved hardness, fracture toughness, thermal stability, and oxidation resistance, have been discussed at length. The review considers grain boundary dynamics and configurational disorder to understand the chemical and electrical properties, highlighting the potential of HECs in energy storage and conversion devices. The exceptional potential of hydroxyapatite as an HEC, with improved bioactivity, controlled resorption rates, and mechanical stability for biomedical applications, is considered. HECs as multipurpose diffusion barriers and coatings with demonstrated resilience to wear, corrosion, and heat are also included in the review. It concludes with perspectives on the latest characterization methods, limitations in existing processing technologies, the role of machine learning, high-throughput synthesis, and additive manufacturing in paving the way for future breakthroughs.