Preparation and electrical output performance of a fast-response triboelectric nanogenerator based on PI/Cu/PVDF composite film

Abstract Conventional triboelectric nanogenerators (TENGs) based on polymer friction layers often suffer from low surface charge density, nonuniform charge distribution and poor environmental stability, which limit their energy harvesting efficiency and real-time power supply capability. Although metals possess high free-electron density and excellent conductivity that favor charge transport and storage, exposed metal films are vulnerable to humidity and airborne charged particles, leading to rapid charge dissipation and increased device complexity. To address these issues, this work proposes a main TENG (M-TENG) based on a PI/Cu/PVDF metal composite film integrated with a pump-type TENG (P-TENG) derived from a TENG with a transition layer (TL-TENG) to enable effective charge injection into the Cu layer. In this structure, PI (Polyimide) acts as a charge-shielding layer; Cu serves as the charge storage unit and PVDF (Polyvinylidene fluoride) functions as both the triboelectric interface and an environmental barrier, improving charge retention and device stability. The influences of PVDF thickness and P-TENG operating frequency on the electrical output of M-TENG were systematically investigated, together with dynamic response, load matching and mechanical durability. With an optimized PVDF thickness of 30 μ m, the device achieved a short-circuit current ( I SC ) of 51.61 μ A, an open-circuit voltage ( V OC ) of 550 V and a transferred charge ( Q ) of 218.38 nC. The output remained nearly independent of P-TENG frequency from 2 to 8 Hz. A maximum power density of 6.9 W m −2 was obtained at 5 MΩ. After 8 × 10 4 cycles, 98.65% of the initial current was retained, demonstrating excellent long-term stability.