Energy harvesting technologies have been explored by researchers for more than two decades as an alternative to conventional power sources (e.g. batteries) for small-sized and low-power electronic devices. The limited life-time and necessity for periodic recharging or replacement of batteries has been a consistent issue in portable, remote, and implantable devices. Ambient energy can usually be found in the form of solar energy, thermal energy, and vibration energy. Amongst these energy sources, vibration energy presents a persistent presence in nature and manmade structures. Various materials and transduction mechanisms have the ability to convert vibratory energy to useful electrical energy, such as piezoelectric, electromagnetic, and electrostatic generators. Piezoelectric transducers, with their inherent electromechanical coupling and high power density compared to electromagnetic and electrostatic transducers, have been widely explored to generate power from vibration energy sources. A topical review of piezoelectric energy harvesting methods was carried out and published in this journal by the authors in 2007. Since 2007, countless researchers have introduced novel materials, transduction mechanisms, electrical circuits, and analytical models to improve various aspects of piezoelectric energy harvesting devices. Additionally, many researchers have also reported novel applications of piezoelectric energy harvesting technology in the past decade. While the body of literature in the field of piezoelectric energy harvesting has grown significantly since 2007, this paper presents an update to the authors' previous review paper by summarizing the notable developments in the field of piezoelectric energy harvesting through the past decade.

https://iopscience.iop.org/article/10.1088/1361-665X/ab36e4/pdf

A review of energy harvesting using piezoelectric materials: state-of-the-art a decade later (2008–2018)

A comprehensive review on the state-of-the-art of piezoelectric energy harvesting

Supercapacitors have become the most significant energy conversion and storage system in recent renewable and sustainable nanotechnology. Due to its large energy capacity and supply with relatively short time and longer lifetime, supercapacitors breakthrough in advance energy applications. This review presents a comparative study of different materials, working principles, analysis, applications, advantages and disadvantages of various technologies available for supercapacitors. The aim of this article is to discuss the possibility of hybrid supercapacitor for the next generation of energy technology. The development of composite materials containing a wide range of active constituents (e.g., graphene, activated carbon, transition metals, metal oxides, perovskites and conducting polymers) by in-situ hybridization and ex-situ recombination is also discussed. This review consecrated largely the contribution of combining all materials (electrode and electrolyte) and their synthesis process and electrochemical performance. Enduringly, the potential issues and the perspectives for future research based on hybrid supercapacitors in energy applications are also presented.

Advanced materials and technologies for hybrid supercapacitors for energy storage – A review

The goal of this paper is to review current methods of energy harvesting, while focusing on piezoelectric energy harvesting The piezoelectric energy harvesting technique is based on the materials' property of generating an electric field when a mechanical force is applied This phenomenon is known as the direct piezoelectric effect Piezoelectric transducers can be of different shapes and materials, making them suitable for a multitude of applications To optimize the use of piezoelectric devices in applications, a model is needed to observe the behavior in the time and frequency domain In addition to different aspects of piezoelectric modeling, this paper also presents several circuits used to maximize the energy harvested

/pdf/piezoelectric-energy-harvesting-solutions-a-review-449lsu70t1.pdf

Piezoelectric Energy Harvesting Solutions: A Review.

https://dr.ntu.edu.sg/bitstream/10220/7680/2/Electrically%20tunable%20dielectric%20materials%20and%20strategies%20to%20improve%20their%20performances.pdf

Electrically tunable dielectric materials and strategies to improve their performances

Lead-free (1− x )Bi 0.5 Na 0.5 TiO 3 – x BaTiO 3 piezoelectric ceramics were investigated for energy-harvesting applications. In order to enhance the piezoelectric properties, the BaTiO 3 content was varied at 0 ≤  x  ≤ 0.1. Furthermore, the sintering temperature was optimized to enhance the piezoelectric properties and output energies. The piezoelectric charge coefficient was enhanced from 70 to 164 pC/N by introducing BaTiO 3 and optimizing the sintering temperature to 1175 °C. The (1 −  x )Bi 0.5 Na 0.5 TiO 3 – x BaTiO 3 lead-free piezoelectric ceramics exhibited a piezoelectric voltage coefficient of 47.03 × 10 −3  V m/N at x  = 0.04, which is slightly higher than the piezoelectric voltage coefficient of lead-based piezoelectric ceramics. The generated output voltage and output power were 8.95 V and 18 nW, respectively, for 0.94Bi 0.5 Na 0.5 TiO 3 –0.06BaTiO 3 ceramics sintered at 1175 °C. The results suggest that lead-free (1 −  x )Bi 0.5 Na 0.5 TiO 3 – x BaTiO 3 piezoelectric ceramics are good candidates for energy-harvesting applications.

(1 − x)Bi0.5Na0.5TiO3–xBaTiO3 lead-free piezoelectric ceramics for energy-harvesting applications

Grain size effects on the dielectric properties of CaCu3Ti4O12 ceramics for supercapacitor applications

Multi-layered piezoelectric energy harvesters based on PZT ceramic actuators

In this study, we investigated (1-x)Ba(Zr0.2Ti0.8)O3–x(Ba0.7Ca0.3)TiO3 lead-free piezoelectric ceramics for energy harvester applications. The (1-x)BZT-xBCT ceramic is a promising lead-free piezoelectric material in the field of piezoelectric energy harvesting. Piezoelectric and energy properties of (1-x)BZT-xBCT ceramics were analyzed to confirm the possibility of using them as energy-harvesting materials. Especially, the vicinity of the phase convergence region was investigated to improve their piezoelectric properties. In the phase convergence region, cubic, rhombohedral, orthorhombic, and tetragonal regions co-exist within the narrow region. Near the phase transition region between the orthorhombic and tetragonal phase, the highest piezoelectric property d33 = 464 pC/N and the highest energy density of 158.5 μJ/cm3 were observed. This output energy density of 158.5 μJ/cm3 is the recorded highest value among lead-free ceramics. We found that the optimal sintering temperature was 1475 °C and the optimal composition was BZT-0.5BCT.

Jung-Hyuk Koh

Papers

(1 − x)Bi0.5Na0.5TiO3–xBaTiO3 lead-free piezoelectric ceramics for energy-harvesting applications

Grain size effects on the dielectric properties of CaCu3Ti4O12 ceramics for supercapacitor applications

Multi-layered piezoelectric energy harvesters based on PZT ceramic actuators

Piezoelectric properties of (1-x)BZT-xBCT system for energy harvesting applications

Enhanced electrical and optical properties based on stress reduced graded structure of Al-doped ZnO thin films