We
present gas-permeable, ultrathin, and stretchable electrodes
enabled by self-assembled porous substrates and conductive nanostructures.
An efficient and scalable breath figure method is employed to introduce
the porous skeleton, and then silver nanowires (AgNWs) are dip-coated
and heat-pressed to offer electric conductivity. The resulting film
has a transmittance of 61%, sheet resistance of 7.3 Ω/sq, and
water vapor permeability of 23 mg cm–2 h–1. With AgNWs embedded below the surface of the polymer, the electrode
exhibits excellent stability in the presence of sweat and after long-term
wear. We demonstrate the promising potential of the electrode for
wearable electronics in two representative applications: skin-mountable
biopotential sensing for healthcare and textile-integrated touch sensing
for human–machine interfaces. The electrode can form conformal
contact with human skin, leading to low skin–electrode impedance
and high-quality biopotential signals. In addition, the textile electrode
can be used in a self-capacitance wireless touch sensing system.
Separators
are key safety components for electrochemical energy storage systems.
However, the intrinsic poor wettability with electrolyte and low thermal
stability of commercial polyolefin separators cannot meet the requirements
of the ever-expanding market for high-power, high-energy, and high-safety
power systems, such as lithium-metal, lithium-sulfur, and lithium-ion
batteries. In this study, scalable bendable networks built with ultralong
silica nanowires (SNs) are developed as stable separators for both
high-safety and high-power lithium-metal batteries. The three-dimensional
porous nature (porosity of 73%) and the polar surface of the obtained
SNs separators endue a much better electrolyte wettability, larger
electrolyte uptake ratio (325%), higher electrolyte retention ratio
(63%), and ∼7 times higher ionic conductivity than that of
commercial polypropylene (PP) separators. Moreover, the pore-rich
structure of the SNs separator can aid in evenly distributing lithium
and, in turn, suppress the uncontrollable growth of lithium dendrites
to a certain degree. Furthermore, the pure inorganic structure endows
the SNs separators with excellent chemical and electrochemical stabilities
even at elevated temperatures, as well as excellent thermal stability
up to 700 °C. This work underpins the utilization of SNs separators
as a rational choice for developing high-performance batteries with
a metallic lithium anode.
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