posted on 2015-02-18, 00:00authored byChun-Peng Yang, Ya-Xia Yin, Yu-Guo Guo, Li-Jun Wan
In contrast to the extensive studies
of the electrochemical behavior
of conventional cyclic S8 molecules in Li–S batteries,
there has been hardly any investigation of the electrochemistry of
S chains. Here we use S chains encapsulated in single- and double-walled
carbon nanotubes as a model system and report the electrochemical
behavior of 1D S chains in Li–S batteries. An electrochemical
test shows that S chains have high electrochemical activity during
lithiation and extinctive electrochemistry compared with conventional
S8. The confined steric effect provides Li+ solid-phase
diffusion access to insert/egress reactions with S chains. During
lithiation, the long S chains spontaneously become short chains, which
show higher discharge plateaus and better kinetics. The unique electrochemistry
of S chains supplements the existing knowledge of the S cathode mechanism
and provides avenues for rational design of S cathode materials in
Li–S batteries.