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 (Eb) 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 Eb 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.

Hybrid nanogenerators based on the principle of surface charging of functional films are significant in self-powering sensing and energy conversion devices due to their multiple functions and high conversion efficiency, although applications remain limited due to a lack of suitable materials and structures. Here, we investigate a triboelectric-piezoelectric hybrid nanogenerator (TPHNG) in the form of a mousepad for computer user behavior monitoring and energy harvesting. Triboelectric and piezoelectric nanogenerators with different functional films and structures work independently to detect sliding and pressing movements, and the profitable coupling between the two nanogenerators leads to enhanced device outputs/sensitivity. Different mouse operations such as clicking, scrolling, taking-up/putting-down, sliding, moving rate, and pathing can be detected by the device via distinguishable patterns of voltage ranging from 0.6 to 36 V. Based on operation recognition, human behavior monitoring is realized, with monitoring of tasks such as browsing a document and playing a computer game being successfully demonstrated. Energy harvesting from mouse sliding, patting, and bending of the device is realized with output voltages up to 37 V and power up to 48 μW while exhibiting good durability up to 20,000 cycles. This work presents a TPHNG utilizing surface charging for self-powered human behavior sensing and biomechanical energy harvesting.

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