[en] Highlights: • A simple process has been developed to incorporate liquid metal particles into PAN nanofibers uniformly. • Liquid metal has been used as nanoparticle dopants to improve the TENG performance significantly • The charge trapping at the liquid metal surface oxide plays the key role for the performance improvement of TENGs. -- Abstract: Liquid metal (LM) has been used as flexible electrodes for high performance triboelectric nanogenerators (TENGs), however it is unclear how the LM in tribo-layers would affect the performance of TENGs. Here, we report the investigation on the effects of LM particles incorporated into a tribo-layer on the performance of TENGs. The TENGs consist of a polyacrylonitrile (PAN) electrospinning nanofiber membrane, and a polytetrafluoroethylene (PTFE) thin film. LM particles with different concentrations are incorporated into PAN polymer matrix, and used to make the PAN nanofibers membranes by electrospinning. Result shows that the outputs of TENGs become much larger with the increase in LM content. Specifically, the current density increases by about 40%, and both the charge density and output voltage increase by nearly 70%. The overall output power is approximately 2 times higher for the TENG with 1.5 wt% LM concentration, as compared to those of TENGs with pure PAN tribo-layer. However, the output of PAN/LM-PTFE TENGs deteriorates drastically when the LM mass content is increased to 2.5 wt%, at which the composite contains a high density of LM spheroid and spindle particles, deteriorating the generation of triboelectric charge.

[en] Highlights: • Different types of electrolytes have been utilized to dope and modulate PVA based solid polymer electrolytes tribolayer to achieve much enhanced transferred charge density of 210 μC m⁻². • The PTFE/PVA-LiCl TENG demonstrates much enhanced triboelectric performance and stability, achieving a high power density of 83 W m⁻². • Electrolyte addition enhances the triboelectric property of PVA based SPE as a positive triboelectric material. • Enhanced interaction between triboelectric layers further improves the outputs of TENGs significantly. -- Abstract: Triboelectric nanogenerators (TENGs), as a promising energy harvesting technology, have attracted considerable attention and various approaches have been developed to improve their output performance. An innovative strategy was proposed recently by using solid polymer electrolyte (SPE) with asymmetric pairing ions as the friction layer, showing excellent potential to achieve high-performance TENGs. However, it is far from clear what are the effects of SPE on TENG performance as only one electrolyte, CaCl₂, was used for the investigation. Herein, PTFE/PVA-MCl_x TENGs based on SPEs with different types of electrolytes, including LiCl, ZnCl₂, CaCl₂, FeCl₃, and AlCl₃, were fabricated and their performances were investigated. All the devices demonstrated superior output performance than that of the control PTFE/PVA TENG. Specifically, the PTFE/PVA-LiCl TENG exhibited remarkably enhanced triboelectric performance with an output voltage of ~1345 V, a short-circuit current density of ~260 mA m⁻² and a maximum power density of ~83 W m⁻², four times higher than that of the control PTFE/PVA TENG. Detailed investigations revealed that in combination with improved triboelectric property, the enhanced interaction of SPEs with opposite triboelectric layers further significantly boost the triboelectric outputs. This work presents a new method to increase the interaction between triboelectric layers to effectively improve the outputs of TENGs, and to facilitate the development of high performance TENGs.

[en] Memristors are an important component of the next-generation artificial neural network, high computing systems, etc. In the past, two-dimensional materials based memristors have achieved a high performance and low power consumption, though one at the cost of the other. Furthermore, their performance can not be modulated frequently once their structures are fixed, which remains the bottleneck in the development. Herein, a series of forming free memristors are fabricated with the same Cu/Fe₃GeTe₂ oxide/Fe₃GeTe₂/Al structure, yet the On/Off ratio and set voltage is modulated continuously by varying the oxidation time during fabrication. With an optimal oxidation time, a large On/Off ratio (1.58 × 10³) and low set voltage (0.74 V) is achieved in a single device. The formation and rapture of Al conductive filaments are found to be responsible for the memristors, and the filaments density and the cross-section area increase with the increase of current compliance, which achieves a higher On/Off ratio. The memristor can imitate basic biological synaptic functions using voltage pulses, demonstrating the potential for low-power consuming neuromorphic computing applications. (paper)