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Economic and social development of nations across the globe is demanding enormous need for energy and power resources. Energy production using safe and renewable sources can aid in mitigating the release of greenhouse gases and avoiding the devastating climate changes. In the present case, a linear type magnetostrictive transducer device is designed by employing Terfenol-D magnetostrictive rods for renewable energy harvesting application. A linear device was designed with two Terfenol-D rods, three permanent magnets (neodymium magnets), springs, and primary and secondary coils. Terfenol-D rod crystallizes in cubic Laves phase and exhibits the saturation magnetostriction value of 1242 × 10−6 at the field of 2.5 kOe. An equivalent circuit is constructed for the induced magnetic flux in the designed transducer device. Frequency and wave form dependent output voltage is examined in the designed energy harvesting device. A square wave at the applied frequency of 2200 Hz (100 mA current) produces a maximum output voltage of 4.91 V. Sine and triangle waves produce 3.38 and 2.82 V, respectively, at 1700 and 1600 Hz. The induced voltage is sufficient to ignite the light emitting diode. A linear type magnetostrictive transducer can be employed as a potential renewable energy source for real-time application with moderate output voltage. [ABSTRACT FROM AUTHOR]

This paper presents the different beam geometries for vibration-excited piezoelectric energy harvesters. The performance of various beam geometries are analysed by comparing frequency analysis, open-circuit voltage, and determination of optimal load, voltage and power under load using experimental and numerical methods. The numerical results are obtained using the FEM software COMSOL Multiphysics 5.3a. From the frequency analysis of various beams by experimental and numerical analysis, it was found that the maximum deviation is about 4.18%. In the open-circuit voltage, TA TW and INTA TW energy harvesters have a minimum and maximum deviation of 0.77% and 9.92% with experimental and numerical methods. From the numerical and experimental results, it was found that the INTA TW energy harvester produces an averagely of 15.63% more power per unit volume compared to the RE energy harvester. From this investigation, it was found that the numerical method has good agreement with the experimental method. [ABSTRACT FROM AUTHOR]

The field of wireless sensors and portable electronics devices gained more attraction and growth over the years. Almost all the devices are powered using chemical batteries. Several energy sources are available in the environment in different parameters, which could be able to convert into an electrical parameter to power the portable devices and wireless sensors. This article reviews the harvesting of vibrational energy and converting it into electrical energy using piezoelectric materials. The sources of energy and conversion mechanism used to convert one type of energy into electrical energy were discussed. The different types of piezoelectric materials, various geometries of the substrate, resonant tuning methods of the harvester, placement of piezoelectric materials, and proof mass on the substrate were also reviewed. [ABSTRACT FROM AUTHOR]

This paper presents the design and development of manual frequency tuneable energy harvester. The energy harvester consists of beam, piezoelectric materials, proof mass, charging circuit, storage device and enclosure box. The design of beam and proof mass was made using the output of previous work and other parts were designed in this work. The energy harvester was developed based on the design and placed into the enclosure box. The fabricated model was tested to know the performance of energy harvester by analysing the output voltage, current, power and charging time of the battery. The distance of proof mass was varied from the fixed end of the cantilever beam to tune the frequency of energy harvester. From the experiment, it was found that the proof mass of energy harvester at 115 mm produced 88.77% more power compared to the proof mass placed at 85 mm from the fixed end. The operating range of energy harvester is about 5 Hz to 30 Hz. The proof mass placed at a distance of 155 mm from the fixed end charge the 60 mAh battery at 65.14% faster compared to the proof mass placed at 85 mm from the fixed end. [ABSTRACT FROM AUTHOR]

• LiFe 5 O 8 thin films exhibits specific discharge capacity of 25 μAh/cm2 at 10 μA/cm2 current density. • Li-ion diffusion coefficient during the de-lithiation and lithiation process is seen to be 3.78 × 10−14 cm2/s and 1.41 × 10−13 cm2/s, respectively. • Li+ storage is dominated by a diffusion-controlled process at low scan rates and it becomes a surface-controlled process at high rates. The search for obtaining a Co free low-cost and high-capacity anode thin film material for high energy density all-solid thin film batteries has been driving the increasing innovation and research in Li-ion battery (LIB) technology. In the present case, LiFe 5 O 8 (LFO) thin films are prepared by pulsed laser deposition (PLD) technique and their electrochemical properties, Li ion dynamics, conducting processes at various frequencies and current rates are explored. LFO thin films are seen to crystallize in ordered α -phase with an inverse spinel structure. Chemical state of all the elements is analysed using X-ray photoelectron spectroscopy method. Cyclic voltammeter (CV) study carried out between 0–3 V shows the reduction peak at 0.76 V initially and in the later cycles at 0.86 V with a small shift depicting the exact conversion type behaviour of the LFO thin film. LFO thin film exhibits specific discharge capacity of 25 μAh/cm2 at 10 μA/cm2 current density during the first cycle. Rate capability measurements are carried out at various current densities of 10, 20, 30, 40, 50 and 10 μA/cm2. Li-ion diffusion coefficient during the de-lithiation and lithiation process is seen to be 3.78 × 10−14 cm2/s and 1.41 × 10−13 cm2/s, respectively. CV studies at various scan rates indicates that the mechanism of Li+ storage is dominated by a diffusion-controlled process at low scan rates and with increasing scan rate it becomes a surface-controlled process. Electrochemical impedance studies at various frequencies shows the decrease in charge transfer resistance with increasing cycles. Combined structural, chemical, electrochemical and impedance studies of LFO thin films indicates that these films can be employed for fabricating Co and Ni free all-solid thin film Li-ion batteries for energy storage applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Dielectric constant of LiFe 5 O 8 increases from 2 × 104 to 3 × 106 with Sr doing. • Dielectric loss decreases considerably with Sr doping in LiFe 5 O 8. • Grain and grain boundary contributions to the conductivity in Sr doped LiFe 5 O 8 is evident. We report on enhanced dielectric constant and reduction in dielectric loss with Sr doping in LiFe 5 O 8 bulk material. LiSr x Fe 5-x O 8 (x = 0, 0.025, 0.05) samples are seen to crystallize in ordered α- LiFe 5 O 8 phase. Dielectric constant is observed to increase from 2 × 104 to 3 × 106 and loss decreases with the doping of Sr at Fe site. Temperature dependent DC conductivity follows the Arrhenius relationship and the activation energy associated with the conduction process is seen to be 0.42, 0.41 and 0.52 eV for the LiSr x Fe 5-x O 8 (x = 0, 0.025, 0.05) samples. Temperature and wide frequency dependent dielectric measurements indicate that the Sr doped LiFe 5 O 8 samples exhibit relaxation behavior and can be employed for high frequency applications. [ABSTRACT FROM AUTHOR]