SuperhierarchicalConductive Framework Implanted withNickel/Graphitic Carbon Nanocages as Sulfur/Lithium Metal Dual-RoleHosts for Li–S Batteries
2020
High-energy-density
Li–S batteries (LSBs) are considered
as a promising next-generation energy-storage system. However, the
sluggish redox kinetics and severe polysulfide shuttle effect in elemental
sulfur cathodes, along with uncontrollable dendrite propagation in
lithium metal anodes, inevitably depress the electrochemical performance
of LSBs and impede their practical implementation. Motivated by a
unique hierarchical geometry, specific chemical affinity, and nitrogen-enriched
collagen component of natural skin fibers (SFs), here we proposed
an effective structural engineering strategy for crafting an SF-derived
superhierarchical N-doped porous carbon framework in situ implanted
with nickel/graphitic carbon nanocages as a dual-role host to simultaneously
address the challenges faced on the sulfur cathode and lithium anode
in LSBs. The experimental results and theoretical calculation disclose
that the implanted Ni nanoparticles and highly graphitic sp2 carbon nanocages together with doped N heteroatoms not only provide
a synergetic trapping-catalytic-conversion effect for regulating soluble
polysulfides with promoted redox kinetics in the cathode at both room
and elevated (55 °C) temperatures but also yield Ni-enhanced
lithiophilic N-heteroatom active sites in the host framework to control
Li deposition and suppress Li dendrite growth in anodes. Combining
the cathodic and anodic improvements further achieves a superb rate
and cycling performance in full LSB cells with stable Coulombic efficiency,
showing great potential in developing reliable LSBs.
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