Research Progress and Prospects of Liquid–Liquid Triboelectric Nanogenerators: Mechanisms, Applications, and Future Challenges

The liquid–liquid triboelectric nanogenerator (L-L TENG) is an emerging nanogeneration technology that converts weak mechanical energy, tidal energy, and other forms of energy into electricity through the frictional interactions between liquids. This paper reviews the research progress of L-L TENG. First, it provides an overview of the working principles of L-L TENG, analyzes its basic working mechanisms, and summarizes its fundamental operation modes while organizing the liquid–liquid materials currently used for charge transfer. Additionally, this paper outlines the applications of L-L TENG in energy harvesting, medicine, and other fields, offering insights for performance enhancement and the expansion of application scenarios. Finally, the paper discusses the challenges facing the development of L-L TENG, as well as its future direction and potential applications. Overall, as an emerging energy conversion technology, L-L TENG has attracted widespread interest from scientists worldwide. This review aims to provide scientists, engineers, and researchers in related fields with a comprehensive perspective to further advance this area of research.