Summary
The nickel‐iron hydroxide‐like catalyst for oxygen evolution reaction (OER) is prepared by an improved coprecipitation method. The crystallization degree of hydrotalcite‐like compound is high, and the lamellar structure is homogeneous with no agglomeration, which helps to build efficient mass‐transfer layer channel of OH ions. The NiFe layered double hydroxide (LDH)/carbon nanotubes (CNTs) electrode shows good performance and stability for OER. The potential of NiFe LDH/CNTs electrode is only 0.592 V (vs HgO/Hg) at 200 mA·cm−2 in 6 mol·L−1 potassium hydroxide (KOH) electrolyte, which shows excellent catalytic activity for OER. The NiFe LDH/CNTs electrode works continuously for 620 hours at 200 mA·cm−2, with the groove voltage only rises 0.1 V.
Lithium–sulfur
batteries (LSBs) hold great potential as
next-generation electrochemical energy storage and conversion systems
owing to their higher theoretical capacity (1675 mAh/g). However,
the shuttling of soluble polysulfides with slow redox reaction kinetics
has restricted the commercialization of LSBs. The design and synthesis
of effective cathode hosts provide a promising solution to improving
the electrochemical performances of LSBs. Herein, we report a composite
of macro/mesoporous carbon (MMC) coupled with defective TiO2 nanoparticles as a novel functional cathode host for LSBs. The MMC/TiO2 composite has been synthesized using a template-based approach
combining simple hydrothermal reactions. Experimental characterizations,
electrochemical measurements, and first-principles density functional
theory (DFT) calculations disclose that the combination of macro/mesoporous
carbon and defective TiO2 (coexistence of oxygen vacancies
and Ti3+) effectively suppresses the undesired polysulfide
shuttling effect and promotes fast redox conversion of polysulfides
during cycling. The resultant LSBs with MMC/TiO2@S as a
composite cathode thus exhibit impressive electrochemical properties
with high capacity (1420 mAh/g at 0.2C), good rate capability (522
mAh/g at 2C), and cycling ability (65.6% retention at 0.2C over 60
cycles). This work can present some new insights into the rational
design and exploration of novel material systems and compositions
for applications in LSBs.
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