24 research outputs found
Mussel-Inspired Polydopamine Coating for Enhanced Thermal Stability and Rate Performance of Graphite Anodes in Li-Ion Batteries
Despite two decades of commercial
history, it remains very difficult
to simultaneously achieve both high rate capability and thermal stability
in the graphite anodes of Li-ion batteries because the stable solid
electrolyte interphase (SEI) layer, which is essential for thermal
stability, impedes facile Li<sup>+</sup> ion transport at the interface.
Here, we resolve this longstanding challenge using a mussel-inspired
polydopamine (PD) coating via a simple immersion process. The nanometer-thick
PD coating layer allows the formation of an SEI layer on the coating
surface without perturbing the intrinsic properties of the SEI layer
of the graphite anodes. PD-coated graphite exhibits far better performances
in cycling test at 60 °C and storage test at 90 °C than
bare graphite. The PD-coated graphite also displays superior rate
capability during both lithiation and delithiation. As evidenced by
surface free energy analysis, the enhanced performance of the PD-coated
graphite can be ascribed to the Lewis basicity of the PD, which scavenges
harmful hydrofluoric acid and forms an intermediate triple-body complex
among a Li<sup>+</sup> ion, solvent molecules, and the PD’s
basic site. The usefulness of the proposed PD coating can be expanded
to various electrodes in rechargeable batteries that suffer from poor
thermal stability and interfacial kinetics
Succinonitrile as a Corrosion Inhibitor of Copper Current Collectors for Overdischarge Protection of Lithium Ion Batteries
Succinonitrile (SN) is investigated
as an electrolyte additive for copper corrosion inhibition to provide
overdischarge (OD) protection to lithium ion batteries (LIBs). The
anodic Cu corrosion, occurring above 3.5 V (vs Li/Li<sup>+</sup>)
in conventional LIB electrolytes, is suppressed until a voltage of
4.5 V is reached in the presence of SN. The corrosion inhibition by
SN is ascribed to the formation of an SN-induced passive layer, which
spontaneously develops on the copper surface during the first anodic
scan. The passive layer is composed mainly of Cu(SN)<sub>2</sub>PF<sub>6</sub> units, which is evidenced by Raman spectroscopy and electrochemical
quartz crystal microbalance measurements. The effects of the SN additive
on OD protection are confirmed by using 750 mAh pouch-type full cells
of LiCoO<sub>2</sub> and graphite with lithium metal as a reference
electrode. Addition of SN completely prevents corrosion of the copper
current collector in the full cell configuration, thereby tuning the
LIB chemistry to be inherently immune to the OD abuses
New Macrobicyclic Chelator for the Development of Ultrastable <sup>64</sup>Cu-Radiolabeled Bioconjugate
Ethylene cross-bridged cyclam with two acetate pendant
arms, ECB-TE2A,
is known to form the most kinetically stable <sup>64</sup>Cu complexes.
However, its usefulness as a bifunctional chelator is limited because
of its harsh radiolabeling conditions. Herein, we report new cross-bridged
cyclam chelator for the development of ultrastable <sup>64</sup>Cu-radiolabeled
bioconjugates. Propylene cross-bridged TE2A (PCB-TE2A) was successfully
synthesized in an efficient way. The Cu(II) complex of PCB-TE2A exhibited
much higher kinetic stability than ECB-TE2A in acid decomplexation
studies, and also showed high resistance to reduction-mediated demetalation.
Furthermore, the quantitative radiolabeling of PCB-TE2A with <sup>64</sup>Cu was achieved under milder conditions compared to ECB-TE2A.
Biodistribution studies strongly indicate that the <sup>64</sup>Cu
complexes of PCB-TE2A cleared out rapidly from the body with minimum
decomplexation
Unraveling the Magnesium-Ion Intercalation Mechanism in Vanadium Pentoxide in a Wet Organic Electrolyte by Structural Determination
Magnesium batteries
have received attention as a type of post-lithium-ion
battery because of their potential advantages in cost and capacity.
Among the host candidates for magnesium batteries, orthorhombic α-V<sub>2</sub>O<sub>5</sub> is one of the most studied materials, and it
shows a reversible magnesium intercalation with a high capacity especially
in a <i>wet</i> organic electrolyte. Studies by several
groups during the last two decades have demonstrated that water plays
some important roles in getting higher capacity. Very recently, proton
intercalation was evidenced mainly using nuclear resonance spectroscopy.
Nonetheless, the chemical species inserted into the host structure
during the reduction reaction are still unclear (i.e., Mg(H<sub>2</sub>O)<sub><i>n</i></sub><sup>2+</sup>, Mg(solvent, H<sub>2</sub>O)<sub><i>n</i></sub><sup>2+</sup>, H<sup>+</sup>, H<sub>3</sub>O<sup>+</sup>, H<sub>2</sub>O, or any combination of these).
To characterize the intercalated phase, the crystal structure of the
magnesium-inserted phase of α-V<sub>2</sub>O<sub>5</sub>, electrochemically
reduced in 0.5 M Mg(ClO<sub>4</sub>)<sub>2</sub> + 2.0 M H<sub>2</sub>O in acetonitrile, was solved for the first time by the ab initio
method using powder synchrotron X-ray diffraction data. The structure
was tripled along the <i>b</i>-axis from that of the pristine
V<sub>2</sub>O<sub>5</sub> structure. No appreciable densities of
elements were observed other than vanadium and oxygen atoms in the
electron density maps, suggesting that the inserted species have very
low occupancies in the three large cavity sites of the structure.
Examination of the interatomic distances around the cavity sites suggested
that H<sub>2</sub>O, H<sub>3</sub>O<sup>+</sup>, or solvated magnesium
ions are too big for the cavities, leading us to confirm that the
intercalated species are single Mg<sup>2+</sup> ions or protons. The
general formula of magnesium-inserted V<sub>2</sub>O<sub>5</sub> is
Mg<sub>0.17</sub>H<sub><i>x</i></sub>V<sub>2</sub>O<sub>5</sub>, (0.66 ≤ <i>x</i> ≤ 1.16). Finally,
density functional theory calculations were carried out to locate
the most plausible atomic sites of the magnesium and protons, enabling
us to complete the structure modeling. This work provides an explicit
answer to the question about Mg intercalation into α-V<sub>2</sub>O<sub>5</sub>
New Bifunctional Chelator for <sup>64</sup>Cu-Immuno-Positron Emission Tomography
A new
tetraazamacrocyclic bifunctional chelator, TE2A-Bn-NCS, was
synthesized in high overall yield from cyclam. An extra functional
group (NCS) was introduced to the <i>N</i>-atom of TE2A
for specific conjugation with antibody. The Cu complex of TE2A-Bn-NCS
showed high kinetic stability in acidic decomplexation and cyclic
voltammetry studies. X-ray structure determination of the Cu-TE2A-Bn-NH<sub>2</sub> complex confirmed octahedral geometry, in which copper atom
is strongly coordinated by four macrocyclic nitrogens in equatorial
positions and two carboxylate oxygen atoms occupy the elongated axial
positions. Trastuzumab was conjugated with TE2A-Bn-NCS and then radiolabeled
with <sup>64</sup>Cu quantitatively at room temperature within 10
min. Biodistribution studies showed that the <sup>64</sup>Cu-labeled
TE2A-Bn-NCS-trastuzumab conjugates maintain high stability in physiological
conditions, and NIH3T6.7 tumors were clearly visualized up to 3 days
by <sup>64</sup>Cu-immuno-positron emission tomography imaging in
animal models
Non-Grignard and Lewis Acid-Free Sulfone Electrolytes for Rechargeable Magnesium Batteries
A major
challenge for developing rechargeable Mg-ion batteries
(MIB) is the lack of suitable electrolytes. We report herein dialkyl
sulfones as non-Grignard and Lewis acid-free MIB electrolytes. In
particular, a dipropyl sulfone (DPSO)/tetrahydrofuran (THF) (1/1,
v/v) solution with MgCl<sub>2</sub> salt exhibits high ionic conductivity
(1.1 mS cm<sup>–1</sup> at 30 °C), Mg cycling efficiency
(>90%), and anodic stability (ca. 3.0 V vs Mg). As evidenced by
single
crystal X-ray diffraction analysis, a novel [Mg(DPSO)<sub>6</sub>]<sup>2+</sup> cation complex balanced by two [MgCl<sub>3</sub>(THF)]<sup>−</sup> anions is identified in the DPSO/THF solution. The
DPSO/THF electrolyte also enables excellent cycle performance (>300
cycles) of a Chevrel phase Mo<sub>6</sub>S<sub>8</sub> cathode and
displays a decent compatibility with an organic cathode (3,4,9,10-perylenetetracarboxylic
dianhydride, PTCDA). Along with the superior electrochemical properties
of the DPSO/THF electrolyte, its innate chemical stability and eco-friendly
nature make it a promising MIB electrolyte
Fire-Inhibiting Nonflammable Gel Polymer Electrolyte for Lithium-Ion Batteries
Herein,
we present a gel polymer electrolyte (GPE) improving nonflammability
of lithium-ion batteries (LIBs) by blocking radical-initiated chain
reactions which cause thermal runaway and finally fire issues. The
polymer that makes up the nonflammable GPE was (1) soluble in carbonate
electrolytes, (2) cross-linkable in the presence of a popularly used
lithium salt such as LiPF6, (3) gelated only with 2 wt
% in electrolytes, and (4) radical-scavenging by its functional side
chains. Electrolytes having the polymer were thermally gelated within
battery cells after the cells were assembled by a conventional way.
LIB cells with the GPE were durable against external thermal and mechanical
shocks without sacrificing cell performances. The high transference
number of lithium ions and liquid-equivalent ionic conductivity of
the GPE at only 2% solid content having a stable solid-electrolyte
interphase layer formed even improved cell performances at normal
operation conditions
Fire-Inhibiting Nonflammable Gel Polymer Electrolyte for Lithium-Ion Batteries
Herein,
we present a gel polymer electrolyte (GPE) improving nonflammability
of lithium-ion batteries (LIBs) by blocking radical-initiated chain
reactions which cause thermal runaway and finally fire issues. The
polymer that makes up the nonflammable GPE was (1) soluble in carbonate
electrolytes, (2) cross-linkable in the presence of a popularly used
lithium salt such as LiPF6, (3) gelated only with 2 wt
% in electrolytes, and (4) radical-scavenging by its functional side
chains. Electrolytes having the polymer were thermally gelated within
battery cells after the cells were assembled by a conventional way.
LIB cells with the GPE were durable against external thermal and mechanical
shocks without sacrificing cell performances. The high transference
number of lithium ions and liquid-equivalent ionic conductivity of
the GPE at only 2% solid content having a stable solid-electrolyte
interphase layer formed even improved cell performances at normal
operation conditions
Fire-Inhibiting Nonflammable Gel Polymer Electrolyte for Lithium-Ion Batteries
Herein,
we present a gel polymer electrolyte (GPE) improving nonflammability
of lithium-ion batteries (LIBs) by blocking radical-initiated chain
reactions which cause thermal runaway and finally fire issues. The
polymer that makes up the nonflammable GPE was (1) soluble in carbonate
electrolytes, (2) cross-linkable in the presence of a popularly used
lithium salt such as LiPF6, (3) gelated only with 2 wt
% in electrolytes, and (4) radical-scavenging by its functional side
chains. Electrolytes having the polymer were thermally gelated within
battery cells after the cells were assembled by a conventional way.
LIB cells with the GPE were durable against external thermal and mechanical
shocks without sacrificing cell performances. The high transference
number of lithium ions and liquid-equivalent ionic conductivity of
the GPE at only 2% solid content having a stable solid-electrolyte
interphase layer formed even improved cell performances at normal
operation conditions
Phosphonate Pendant Armed Propylene Cross-Bridged Cyclam: Synthesis and Evaluation as a Chelator for Cu-64
A propylene cross-bridged macrocyclic
chelator with two phosphonate
pendant arms (PCB-TE2P) was synthesized from cyclam. Various properties
of the synthesized chelator, including Cu-complexation, Cu-complex
stability, <sup>64</sup>Cu-radiolabeling, and in vivo behavior, were
studied and compared with those of a previously reported propylene
cross-bridged chelator (PCB-TE2A)