Although
there has been rapid advancement in wearable electronics, challenges
still remain in developing wearable and sustainable power sources
with simple fabrication and low cost. In this work, we demonstrate
a flexible coaxial fiber by fabricating a one-dimensional triboelectric
nanogenerator (TENG) outside and a supercapacitor (SC) inside, which
can not only harvest mechanical energy but also store energy in the
all-in-one fiber. In such a coaxial fiber, carbon fiber bundles are
utilized as the electrode material for the TENG as well as the active
and electrode material for the SC. Meanwhile, silicone rubber serves
as the separator between the SC and TENG, as the triboelectric material
for the TENG, and as the encapsulation material for the whole fiber
as well. Moreover, both SC and TENG exhibit good performance and stability,
which ensures their long-term use in daily life. Because of the flexibility
and durability of the carbon fiber and silicone rubber, the proposed
coaxial fibers show great flexibility, which could be further knitted
as cloth for sustainably powering wearable electronic devices. This
work presents a promising platform for wearable electronics as well
as smart textiles.