Pressure sensors with desirable flexibility, robustness,
and versatility
are urgently needed for complicated smart wearable devices. However,
developing an ideal multifunctional flexible sensor is still challenging.
In this work, a composite aerogel film sensor with an internal three-dimensional
(3D) microporous and hierarchical structure is successfully fabricated
by the self-assembly of aramid nanofiber (ANF) and conductive MXene
by vacuum-assisted filtration and ice crystal growth. The resultant
MXene/ANF aerogel film with a mass ratio of 3/7 (30% MAAF) presents
high robustness with an outstanding tensile strength of 14.1 MPa and
a modulus of 455 MPa while retaining appealing flexibility and sensitive
characteristics due to the 3D microstructure. Accompanied by superior
electric conductivity, the MAAF sensor performs noticeably in human
motion and microexpression detection with a fast response time of
100 ms and a high sensitivity of 37.4 kPa–1. In
addition, MAAF exhibits considerable thermal shielding performance
based on the excellent thermostability. Moreover, it possesses prominent
electrothermal property with a wide heating temperature range (32.7–242
°C) in a fast thermal response time (5 s) due to the Joule effect.
Additionally, a hydrophobic SiO2 coating is introduced
on the surface of MAAF to further broaden the sensing application,
and the obtained MAAF@SiO2 sensor shows distinguished sensing
capability underwater, which can be accurately applied to swimming
monitoring. Therefore, this work provides a highly flexible, lightweight,
robust, and multifunctional aerogel film sensor, showing promising
potential in smart wearable sensing and healthcare devices, intelligent
robots, and underwater detection.
Separators are essential for supplying ion transport
channels and
preventing short circuits. Despite considerable effort, high-performance
separators with desirable overall properties such as excellent thermostability,
wettability, and impressive properties for suppressing lithium dendrites
and polysulfide intermediates remain elusive. Here, we present an
aramid nanofiber (ANF) and metal–organic framework (MOF) composite
separator (ANF@MOFs) utilizing in situ growth of MOFs onto the extremely
porous ANF network substrate. Benefiting from the features of the
excellent strength, modulus, and nanoporosity of the ANF network,
as well as the enormous specific surface area and sufficient metal
sites of MOFs, the resultant ANF@MOFs separator exhibits excellent
mechanical strength (a tensile strength of 110.7 MPa and a modulus
of 3.1 GPa), improved liquid electrolyte wettability (an electrolyte
uptake of 258.3%), and exceptional thermal stability (dimensionally
stable after heating at 200 °C for 0.5 h). The ANF@MOFs separator
not only demonstrates promising capabilities for physically blocking
and chemically adsorbing Li2S2/Li2S and hence suppressing the Li2S
x
shuttle effect but also suppresses the perforation of lithium
dendrites, resulting in remarkable electrochemical and safety features.
The battery equipped with the ANF@MOFs separator has a high first-cycle
discharge capacity of 1081.92 mAh g–1 and a prolonged
cycling performance with a capacity of 876.36 mAh g–1 at 0.5 C after 200 cycles. As a result, the high-performance ANF@MOFs
composite separator provides significant potential for future lithium–sulfur
batteries.
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