Although triboelectric nanogenerators (TENGs) have been developed rapidly and widely used in sensors and energy collection, the surface wear is severe. In this work, a hexadecane-containing sandwich structure based TENG (HS-TENG) has been fabricated by adding a liquid film of hexadecane onto the surface of nylon. The service lifetime of the HS-TENG is more than 10 times longer than that of the traditional TENG, and meanwhile, the maximum produced voltage and power increased by 2.3 and 10.9 times in comparison to the traditional TENG, respectively. The friction coefficient decreases by 73%, and the maximum conversion efficiency increases by more than 50 times. The improved output is mainly attributed to the confined hexadecane film inhibiting wear and transfer of polytetrafluoroethylene (PTFE), and meanwhile, the transfer of triboelectric charges from the triboelectric layer to the hexadecane film enhancing the surface charge density. This work provides an understanding of the charge carrier behavior at the solid-liquid interface, and also provides a method for the optimization of the TENGs by the boundary lubrication. • Hexadecane-containing sandwich structure increase power and conversion efficiency by 10 and 50 times, respectively. • Service lifetime of HS-TENG is increased by 10 times by using boundary lubrication. • Triboelectric charges transfer from the triboelectric layer to the hexadecane film. • Triboelectric charges in the hexadecane film diffuse into the air. • Wear and transfer of polytetrafluoroethylene are inhibited by confined hexadecane film.