High-performance flexible triboelectric nanogenerator driven by the micro-capacitance effect of liquid metal

Liquid metal nanodroplets (LMND) offer exceptional potential for enhancing triboelectric nanogenerators (TENG) due to their intrinsic fluidity and high electrical conductivity, yet the underlying mechanism governing their performance enhancement remains elusive. Here, we propose a "pressure-induced deformation capacitance" mechanism, achieved by uniformly confining LMND within thermoplastic polyurethane (TPU) nanofibers. Under external pressure, the flexible TPU matrix induces controlled deformation of embedded LMND while effectively preventing their leakage, forming a dynamically optimized micro-capacitance network that significantly enhances charge storage capacity. Atomic force microscopy mechanical mapping confirms this effect is exclusive to low Young's modulus matrices. Electrical characterization revealed that the size dependence is not monotonic. Both the capacitive sensitivity of the composite and the TENG output follow a Lorentzian distribution, with the peak occurring when the ratio of the LMND size to the TPU fiber diameter reaches 120%. The optimized TENG exhibits a 28-fold voltage enhancement and a power density of 33.98 W/m². We further develop an origami-structured TENG (270 mg) capable of powering 100 LEDs and demonstrate a self-powered sensing system via functionally decoupled electrode design. This work establishes fundamental design principles for high-performance flexible energy devices and provides a framework for their application in advanced human–machine interfaces.