A hollow NiO nanosphere constructed electrode exhibits high charge–discharge capacities, cycling and rate performance in lithium ion rechargeable batteries.
Polymer binders for sulfur cathodes play a very critical role as they prerequisites for an in-situ immobilization against polysulfide shuttle and volume change, while ensuring good adhesion within active materials for ion conduction along with robust mechanical and chemical stability. Here, we demonstrate anionic surface charge facilitated bio-polymer binder for sulfur cathodes enabling excellent performance and fire safety improvement. The aqueous-processable tragacanth gum-based binder is adjusted to house high sulfur loading over 12 mg cm−2 without compromising the sulfur utility and reversibility, imparting high accessibility for Li-ions to sulfur particles about 80%. The intrinsic rod and sphere-like saccharidic conformal fraction’s multifunctional polar units act as active channels to reach the sulfur particles. As a result, the binder entraps polysulfides with 46% improvement and restrains the volume changes within 16 % even at 4 C. Moreover, the flexible Li-S battery delivers a stack gravimetric energy density of 243 Wh kg–1, demonstrating high reactivity of sulfur along with good shape conformality, which would open an avenue for the potential development of the compact and flexible high-power device.
A phenomenon
is observed in which the electrochemical performances
of porous graphene electrodes show unexpectedly increasing capacities
in the Li storage devices. However, despite many studies, the cause
is still unclear. Here, we systematically present the reason for the
capacity enhancements of the pristine graphene anode under functional
group exclusion through morphological control and crystal structure
transformation. The electrochemical synergy of both the edge effect
and surface effect of the reduced dimensional scale graphene in an
open-porous structure facilitates significantly enhanced capacity
through multidimensional Li-ion accessibility and accumulation of
Li atoms. Furthermore, the Stone–Wales defects boosted during
Li insertion and extraction promote a capacity elevation beyond the
theoretical capacity of the carbon electrode even after long-term
cycles at high C-rates. As a result, the morphologically controlled
graphene anode delivers the highest reversible capacity of 3074 mA
h g–1 with a 163% capacity increase after 2000 cycles
at 5 C. It also presents a gradually increasing capacity up to 1102
mA h g–1 even at 50 C without an evident capacity
fading tendency. This study provides valuable information into the
practical design of ultralight and high-rate energy storage devices.
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