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This article presents a comprehensive study on the impact of antioxidants (AOs) on the aging process of insulating polymeric materials, specifically complex permittivity, conductivity, and ac breakdown (BD) voltage. Accelerated aging was achieved through high temperatures (up to $130~^{\circ }$ C) in the air on crosslinked polyethylene (XLPE) both with and without AOs. In addition to electrical tests, chemical analyses were performed to better understand the role of AOs during thermal aging. The results indicate that AOs effectively inhibit oxidation, preventing the formation of degradation species. As long as AOs are present, minimal changes in the electrical properties are observed. However, once the AOs are almost completely depleted, oxidation products significantly alter the electrical properties, resulting in a worsening of the material electrical performance.

Bipolar carrier models for charge transport simulation in polymers have been developed for several years, but rarely consider the effect of ionization charges inside the polymer. In this report, based on the measurement results of actual ionization charges transport by blocking electrode injection, a modified bipolar carrier transport model is proposed, in which the influence of ionization charge is also considered. The model takes into account the recombination between the ionization charges and the injected carriers as well as the secondary ionization of the recombination products and develops a bipolar carrier transport model that fully considers the influence of the ionization charges. For practical engineering purposes, some simplifications are made to the precision model obtaining an approximated engineering model that can be more simply directly used. At the same time, the criterion of whether the engineering model can be used to replace the precision model is given. This work fills a crucial gap in the existing bipolar carrier transport model.

One of the main issues of wearable electronic devices regards their power supply and autonomy. The exploitation of mechanical energy from body motion and vibrations can be realized by using piezoelectric materials coupled with a proper energy storage device. To this aim, Self-Powered Supercapacitors (SPSCs) have been investigated over the last decades, either as internally integrated SPSC (iSPSC), where the piezoelectric element of the device is used as Super Capacitor (SC) separator, or via an external integration (eSPSC), where the piezoelectric unit and the SC are connected by a bridge rectifier. In this paper, an eSPSC power supply is developed by integrating a stuck of commercial ceramic piezoelectric disks and an ionic liquid-based micro-SC. In detail, a stack of 15 commercial lead zirconate titanate (PZT) disks is used as the energy harvesting unit and mechanically stressed by a compressive force of 85 N at 2 Hz. The piezoelectric output successfully charged the 22 mF supercapacitor up to 3.1 V after 2 h of test, achieving a stored energy value equal to 110 mJ. The proposed integrated system outperforms the state-of-the-art SPSC assembled with micro-SC (both iSPSC and eSPSC). The use of the two different units (piezo-energy harvesting unit and micro-SC energy storage unit) allows an independent sizing and tuning of the supercapacitor according to the output current of the piezoelectric unit.

Solid polymer electrolytes in lithium batteries have the dual function of electrolyte and separator to hinder lithium dendrite growth that causes hazardous short circuits during repeated charge/discharge cycles. Given the good compatibility between polyvinylidene difluoride (PVdF) and polyethylene oxide (PEO) and with the aim to merge the properties of these two polymers, we prepared and characterized PVdF/PEO membranes that act as separators and as hybrid gel polymer electrolytes when soaked in the liquid electrolyte with lithium salt. The membranes based on the polymer blends were prepared by electrospinning, a technique that yields micro-nanofibrous membranes with high porosity and, hence, huge values of electrolyte uptake. PEO 100,000 and PEO 1,000,000 were used to prepare two blends with PVdF:PEO 90:10 w/w composition. The electrochemical performance of the membranes, which were soaked in 1M LiPF6 - ethylene carbonate:dimethyl carbonate (1:1 w/w), was evaluated in Li//LiFePO4 and graphite//LiFePO4 cells and discussed.

Solid polymer electrolytes in lithium batteries have the dual function of electrolyte and separator to hinder lithium dendrite growth that causes hazardous short circuits during repeated charge/discharge cycles. Given the good compatibility between polyvinylidene difluoride (PVdF) and polyethylene oxide (PEO) and with the aim to merge the properties of these two polymers, we prepared and characterized PVdF/PEO membranes that act as separators and as hybrid gel polymer electrolytes when soaked in the liquid electrolyte with lithium salt. The membranes based on the polymer blends were prepared by electrospinning, a technique that yields micro-nanofibrous membranes with high porosity and, hence, huge values of electrolyte uptake. PEO 100,000 and PEO 1,000,000 were used to prepare two blends with PVdF:PEO 90:10 w/w composition. The electrochemical performance of the membranes, which were soaked in 1M LiPF6 – ethylene carbonate:dimethyl carbonate (1:1 w/w), was evaluated in Li//LiFePO4and graphite//LiFePO4cells and discussed.