Li–S
battery has tremendous application prospect on account
of the high theoretical specific capacity and large energy density,
while its large-scale application is impeded by the severe shuttle
effect and the slow electrochemical kinetics of polysulfides conversion.
Herein, the Lewis acidic yttria hollow spheres (YHS) are rationally
designed as both sulfur immobilizer and catalyst of polysulfides conversion
for the advanced Li–S batteries. It can be known that the Lewis
acidic yttria can effectively capture the Lewis basic polysulfides
and thus mitigate the shuttle effect of Li–S battery; besides,
yttria shows the enhanced catalytic effect for the kinetics of interconversion
reaction from polysulfides to Li2S. As a result, either
as a sulfur host or as the separator coating, yttria plays a vital
part in realizing the high specific discharge capacity and good cycle
stability for Li–S battery. In particular, Li–S battery
with YHS@C/S cathode and YHS/CNT-0.6- modified separator (2.1 mg cm–2 active material loading) shows a good specific discharge
capacity of 912.5 mAh g–1 at 0.5C. Even after 200
steady cycles, the discharge specific capacity can keep as 842.3 mAh
g–1, and the capacity decay rate is only 0.038%
per cycle. When active material areal loading is increased to 4.24
mg cm–2, it still maintains a considerable areal
capacity of 3.79 mAh cm–2. In consequence, the synergy
of polysulfides confinement and catalytic conversion reaction provides
a meaningful exploration for achieving the high performance of Li–S
batteries.