Ti3C2T
x
MXene, with high conductivity
and flexibility, has drawn great attention in the wearable energy
storage devices. However, the easy nanoflake-restacking phenomenon
greatly restricts the achievable electrochemical performance of Ti3C2T
x
-based supercapacitors,
in particular volumetric capacitance. Herein, we report a flexible
hybrid paper consisting of Fe2O3 nanoparticles
(NPs) anchored on Ti3C2T
x
(Fe2O3 NPs@MX) via electrostatic
self-assembly and annealing treatments. The interlayer spacing of
Ti3C2T
x
nanoflakes
is effectively enlarged through the incorporation of Fe2O3 NPs, allowing more electrochemical active sites to
store charge. Meanwhile, Ti3C2T
x
nanoflakes form a continuous metallic skeleton and
inhibit the volume expansion of Fe2O3 NPs during
the charging/discharging process, enhancing the cycling stability.
The flexible, ultrathin (4.1 μm) Fe2O3 NPs@MX hybrid paper shows considerably improved electrochemical
performances compared to those of pure Ti3C2T
x
and Fe2O3, including
a wide potential window of 1 V, an ultrahigh volumetric capacitance
of ∼2607 F cm–3 (584 F g–1), and excellent capacitance retention after 13,000 cycles. Besides,
the as-assembled symmetric solid-state supercapacitor exhibits an
energy density of 29.7 Wh L–1 and excellent mechanical
flexibility. We believe that the present nanostructure design, decorating
NPs within a two-dimensional metallic network, has general applicability
and could be used to fabricate highly efficient composites for advanced
energy storage devices.