In this study, a flower-like TiO₂ filled polymethyl methacrylate (PMMA) composite is presented as a positive tribo-material to produce an excellent-performance triboelectric nanogenerator (TENG).

Implantable medical devices have played an important role in human medicine in recent decades. However, traditional implanted devices require battery replacement and a second surgery for device removal, which can cause pain to the patient. This work presents a biodegradable triboelectric nanogenerator (BI-TENG) made from both natural and synthetic biodegradable materials that is utilized to collect mechanical energy in vivo and transduce it into electricity. Reed film and polylactic acid were chosen among different biodegradable materials as the triboelectric layers due to having the best generator output performance by providing voltages that reached 368 V. The biocompatibility of the friction layer and the device was verified via a blood test. After implantation in mice, the BI-TENG exhibited an open-circuit voltage of 0.176 V and a short-circuit current of 192 nA as generated from body movement. The BI-TENG was connected to an interdigital electrode to generate an electric field, which stimulated the accelerated release of doxorubicin (DOX) from red blood cells in targeted drug delivery systems. After stopping the electric field, the release of DOX normalized, facilitating the precise killing of cancer cells. Our work demonstrates the broad potential of BI-TENGs in the field of cancer treatment.

Ionic liquid (IL) electrolytes have enormous potential for the development of high energy density supercapacitors (SCs) owing to their wide potential windows, but ILs are plagued by sluggish ionic diffusion due to their high viscosity and large ion size. Exploiting superwettable electrodes possessing high compatibility with IL electrolytes remains challenging. Inspired by the biological characteristics observed in nature, a unique film electrode with a Monstera leaf-like nanostructure is synthesized and used to overcome the aforementioned bottleneck. Similar to the pores in Monstera leaves that allow the permeation of air and water vapor, the film electrode is based on porous g-C₃N₄ nanosheets (~1 nm thick) as ion-accessible “highway” channels, allowing ultrafast diffusion of IL ions. The film exhibits a high diffusion coefficient (3.68 × 10⁻¹⁰ m² s⁻¹), low activation energy (0.078 mJ mol⁻¹) and extraordinary wettability in the IL electrolyte, indicating its superior IL ion dynamics. As a proof of concept, flexible ionogel SCs (FISCs) with tailorability and editability are fabricated, which exhibit a high energy density (10.5 mWh cm⁻³), high-power density, remarkable rate capability, and long-term durability, outperforming previously reported FISCs. Importantly, these FISCs can be effectively charged by harvesting sustainable power sources, particularly the rarely studied wind power, for practical applications.

Dielectric substances exhibit great potential for high-power capacitors due to their high stability and fast charge–discharge; however, a long-term challenge is to enhance energy density. Here, we propose a poly(vinylidene fluoride) (PVDF) composite utilizing BaTiO₃ nanoparticle@TiO₂ nanosheet (BT@TO ns) 2D nanohybrids as fillers, aiming at combining the interfacial strategy of using a core–shell filler and the electron scattering of a 2D filler to improve the energy density. With 4 wt% filler, the composite possesses the largest breakdown strength (E_b) of 561.2 MV m⁻¹, which is significantly enhanced from the 407.6 MV m⁻¹ of PVDF, and permittivity of 12.6 at 1 kHz, which is a 23% increase from that of PVDF. A superhigh energy density of 21.3 J cm⁻³ with an efficiency of 61% is obtained at 550 MV m⁻¹. The 2D BT@TO ns-filled composite exhibits a higher energy density than composites filled with core–shell 1D BT@TO nws or non-core–shell 0D BT, 1D TO, or 2D TO particles. The E_b and energy density improvements are attributed to the buffer layer-based interface engineering and enhanced area scattering of electrons caused by the 2D hybrids, an effect similar to that of a ping-pong paddle to scatter electric field-induced charge migrations in composites. Thus, an effective hybrid strategy is presented for achieving high-performance polymer composites that can be used in energy storage devices.

Polymer-matrix dielectric composites are promising for use in electrostatic energy storage devices due to the ultra-fast charge–discharge speed and the long service life. Here we report a strategy for designing BaTiO₃ sponge polymer composites for energy storage. BaTiO₃ sponges with tunable porosities are prepared from polymethyl methacrylate micro-sphere arrays. Liquid epoxy completely fills the pores in a BaTiO₃ sponge during vacuum de-foaming, forming a solid composite. The resulting composites possess a maximum dielectric constant of ε_r~332 and ε_r/ε_m~85, compared to ε_r~38 in a sample filled with BaTiO₃ NPs, at 1 kHz. The composites also possess, at 100 kV cm⁻¹, a high discharge energy density of U_d~105 × 10⁻³ J cm⁻³ and U_d/U_m~51, and electric displacement of 3.2 μC cm⁻², compared with those utilizing traditional strategies at low electric fields. Finite element simulation reveals the enhanced energy density is due to a high local electric displacement in composites.