2 research outputs found
Graphene Oxides Used as a New “Dual Role” Binder for Stabilizing Silicon Nanoparticles in Lithium-Ion Battery
For the first time,
we report that graphene oxide (GO) can be used as a new “dual-role”
binder for Si nanoparticles (SiNPs)-based lithium-ion batteries (LIBs).
GO not only provides a graphene-like porous 3D framework for accommodating
the volume changes of SiNPs during charging/discharging cycles, but
also acts as a polymer-like binder that forms strong chemical bonds
with SiNPs through its Si–OH functional groups to trap and
stabilize SiNPs inside the electrode. Leveraging this unique dual-role
of GO binder, we fabricated GO/SiNPs electrodes with remarkably improved
performances as compared to using the conventional polyvinylidene
fluoride (PVDF) binder. Specifically, the GO/SiNPs electrode showed
a specific capacity of 2400 mA h g<sup>–1</sup> at the 50th
cycle and 2000 mA h g<sup>–1</sup> at the 100th cycle, whereas
the SiNPs/PVDF electrode only showed 456 mAh g<sup>–1</sup> at the 50th cycle and 100 mAh g<sup>–1</sup> at 100th cycle.
Moreover, the GO/SiNPs film maintained its structural integrity and
formed a stable solid–electrolyte interphase (SEI) film after
100 cycles. These results, combined with the well-established facile
synthesis of GO, indicate that GO can be an excellent binder for developing
high performance Si-based LIBs
Phase-Transfer Ligand Exchange of Lead Chalcogenide Quantum Dots for Direct Deposition of Thick, Highly Conductive Films
The
use of semiconductor nanocrystal quantum dots (QDs) in optoelectronic
devices typically requires postsynthetic chemical surface treatments
to enhance electronic coupling between QDs and allow for efficient
charge transport in QD films. Despite their importance in solar cells
and infrared (IR) light-emitting diodes and photodetectors, advances
in these chemical treatments for lead chalcogenide (PbE; E = S, Se,
Te) QDs have lagged behind those of, for instance, II–VI semiconductor
QDs. Here, we introduce a method for fast and effective ligand exchange
for PbE QDs in solution, resulting in QDs completely passivated by
a wide range of small anionic ligands. Due to electrostatic stabilization,
these QDs are readily dispersible in polar solvents, in which they
form highly concentrated solutions that remain stable for months.
QDs of all three Pb chalcogenides retain their photoluminescence,
allowing for a detailed study of the effect of the surface ionic double
layer on electronic passivation of QD surfaces, which we find can
be explained using the hard/soft acid–base theory. Importantly,
we prepare highly conductive films of PbS, PbSe, and PbTe QDs by directly
casting from solution without further chemical treatment, as determined
by field-effect transistor measurements. This method allows for precise
control over the surface chemistry, and therefore the transport properties
of deposited films. It also permits single-step deposition of films
of unprecedented thickness via continuous processing techniques, as
we demonstrate by preparing a dense, smooth, 5.3-ÎĽm-thick PbSe
QD film via doctor-blading. As such, it offers important advantages
over laborious layer-by-layer methods for solar cells and photodetectors,
while opening the door to new possibilities in ionizing-radiation
detectors