As one of the most promising energy storage devices,
graphene-based
fibrous supercapacitors (FSSCs) are attracting intensive attention.
However, the conflict between specific capacitance and intrinsic brittleness
of pure graphene fibers hinders their practical applications. Herein,
we develop a strategy to fabricate graphene-based ternary composite
CNT/MXene/graphene (CMG) fiber electrodes with high toughness and
high electrical and electrochemical performance. These resulting properties
are attributed to the three-dimensional cross-linked conducting network
within graphene sheets through covalent bonding and π–π
interaction among acidified carbon nanotubes, graphene sheets, and
MXene, which greatly contributes to the enhanced tensile strength,
toughness, and electrical transport in the CMG fiber. The CMG fiber
with the optimized mass ratio of different components shows a high
toughness of ∼1.7 MJ m–3 and an electrical
conductivity of 420 S cm–1, which is 4- and 2-fold
that of reduced graphene oxide fiber, respectively. The assembled
FSSC based on the optimized CMG fiber exhibits an areal capacitance
of 237 mF cm–2 and a good rate performance of 85%.