3 research outputs found
Cu Microbelt Network Embedded in Colorless Polyimide Substrate: Flexible Heater Platform with High Optical Transparency and Superior Mechanical Stability
Metal nanowires have
been considered as essential components for flexible transparent conducting
electrodes (TCEs) with high transparency and low sheet resistance.
However, large surface roughness and high interwire junction resistance
limit the practical use of metal wires as TCEs. Here, we report Cu
microbelt network (Cu MBN) with coalescence junction and low surface
roughness for next-generation flexible TCEs. In particular, the unique
embedded structure of Cu MBN in colorless polyimide (cPI) film was
achieved to reduce the surface roughness as well as enhance mechanical
stability. The TCEs using junction-free Cu MBN embedded in cPI exhibited
excellent mechanical stability up to 100 000 bending cycles,
high transparency of 95.18%, and a low sheet resistance of 6.25 Ω
sq<sup>–1</sup>. Highly robust Cu MBN-embedded cPI-based TCE
showed outstanding flexible heater performance, i.e., high saturation
temperature (120 °C) at very low voltage (2.3 V), owing to the
high thermal stability of cPI and excellent thermal conductivity of
the Cu MBN
Direct Realization of Complete Conversion and Agglomeration Dynamics of SnO<sub>2</sub> Nanoparticles in Liquid Electrolyte
The conversion reaction is important
in lithium-ion batteries because
it governs the overall battery performance, such as initial Coulombic
efficiency, capacity retention, and rate capability. Here, we have
demonstrated in situ observation of the complete conversion reaction
and agglomeration of nanoparticles (NPs) upon lithiation by using
graphene liquid cell transmission electron microscopy. The observation
reveals that the Sn NPs are nucleated from the surface of SnO<sub>2</sub>, followed by merging with each other. We demonstrate that
the agglomeration has a stepwise process, including rotation of a
NP, formation of necks, and subsequent merging of individual NPs
Brush-Like Cobalt Nitride Anchored Carbon Nanofiber Membrane: Current Collector-Catalyst Integrated Cathode for Long Cycle Li–O<sub>2</sub> Batteries
To achieve a high
reversibility and long cycle life for lithium–oxygen
(Li–O<sub>2</sub>) batteries, the irreversible formation of
Li<sub>2</sub>O<sub>2</sub>, inevitable side reactions, and poor charge
transport at the cathode interfaces should be overcome. Here, we report
a rational design of air cathode using a cobalt nitride (Co<sub>4</sub>N) functionalized carbon nanofiber (CNF) membrane as current collector-catalyst
integrated air cathode. Brush-like Co<sub>4</sub>N nanorods are uniformly
anchored on conductive electrospun CNF papers via hydrothermal growth
of CoÂ(OH)F nanorods followed by nitridation step. Co<sub>4</sub>N-decorated
CNF (Co<sub>4</sub>N/CNF) cathode exhibited excellent electrochemical
performance with outstanding stability for over 177 cycles in Li–O<sub>2</sub> cells. During cycling, metallic Co<sub>4</sub>N nanorods
provide sufficient accessible reaction sites as well as facile electron
transport pathway throughout the continuously networked CNF. Furthermore,
thin oxide layer (<10 nm) formed on the surface of Co<sub>4</sub>N nanorods promote reversible formation/decomposition of film-type
Li<sub>2</sub>O<sub>2</sub>, leading to significant reduction in overpotential
gap (∼1.23 V at 700 mAh g<sup>–1</sup>). Moreover, pouch-type
Li-air cells using Co<sub>4</sub>N/CNF cathode stably operated in
real air atmosphere even under 180° bending. The results demonstrate
that the favorable formation/decomposition of reaction products and
mediation of side reactions are hugely governed by the suitable surface
chemistry and tailored structure of cathode materials, which are essential
for real Li–air battery applications