Three‐Phase Interfacial Force Regulated Solid‐Like Liquid‐Slider for Highly Efficient and Robust Triboelectric Nanogenerator

Abstract Conventional sliding mode triboelectric nanogenerators convert low‐frequency mechanical energy into electricity through relative motion between solid‐solid tribo‐layers. However, the inherent trade‐off between maintaining close contact and mitigating interfacial friction hinders the device's energy conversion efficiency and long‐term stability. Here, a solid‐like liquid‐slider triboelectric nanogenerator (LS‐TENG) is proposed, where milliliter‐scale liquid motion is precisely governed by a liquid‐driver consisting of a hydrophilic interface enclosed by a hydrophobic boundary. By theoretical analysis and experimental regulation of solid–liquid–gas three‐phase interfacial forces, stable operation of the liquid‐slider with a designed pattern is realized as the tilt angle varies from horizontal to vertical. Benefiting from the shape‐adaptivity and ultra‐smooth properties of the liquid, a palm‐sized LS‐TENG outputs 2856 µJ of energy per cycle with an average torque of just 0.73 mN·m at 30 rpm, achieving a record‐high energy conversion efficiency of 63.47%. The optimized friction during solid‐liquid dynamic interactions ensures the excellent stability of LS‐TENG over six months of continuous operation. Moreover, the encapsulated LS‐TENG autonomously initiates under a 1.3 m s −1 breeze, powering 960 series‐connected green LEDs and enabling wireless wind speed monitoring. The regulation of three‐phase interfacial forces in solid‐liquid TENG provides a feasible path for efficient and reliable mechanical energy harvesting.