Mechanical friction-reduction strategies in triboelectric nanogenerators for enhancing efficiency and durability: A comprehensive review

Triboelectric nanogenerators (TENGs) are a promising technology for harvesting ambient mechanical energy, yet their durability is fundamentally limited by friction-induced wear at functional interfaces. Friction in TENGs is inherently paradoxical: it enables charge generation while simultaneously accelerating material degradation. This review systematically summarizes five advanced mechanical friction-reduction strategies developed to address this paradox, including rolling friction, soft contact, intermittent contact, non-contact and interface lubrication. Each friction-reduction strategy is systematically evaluated with respect to the corresponding structural design, operating mechanism and application scenarios in insulator- and semiconductor-based TENGs. Furthermore, a comparative evaluation is conducted to provide a foundational understanding of how friction-reduction methods influence the performance of TENGs and to guide future design optimization. In addition, we outlook the emerging trends toward intelligent, integrated triboelectric energy systems and present a roadmap for practical implementation and commercialization. This review offers valuable insights into the path forward for achieving highly efficient and long-term durable TENGs.