Separators are essential for supplying ion transport
channels and
preventing short circuits. Despite considerable effort, high-performance
separators with desirable overall properties such as excellent thermostability,
wettability, and impressive properties for suppressing lithium dendrites
and polysulfide intermediates remain elusive. Here, we present an
aramid nanofiber (ANF) and metal–organic framework (MOF) composite
separator (ANF@MOFs) utilizing in situ growth of MOFs onto the extremely
porous ANF network substrate. Benefiting from the features of the
excellent strength, modulus, and nanoporosity of the ANF network,
as well as the enormous specific surface area and sufficient metal
sites of MOFs, the resultant ANF@MOFs separator exhibits excellent
mechanical strength (a tensile strength of 110.7 MPa and a modulus
of 3.1 GPa), improved liquid electrolyte wettability (an electrolyte
uptake of 258.3%), and exceptional thermal stability (dimensionally
stable after heating at 200 °C for 0.5 h). The ANF@MOFs separator
not only demonstrates promising capabilities for physically blocking
and chemically adsorbing Li2S2/Li2S and hence suppressing the Li2S
x
shuttle effect but also suppresses the perforation of lithium
dendrites, resulting in remarkable electrochemical and safety features.
The battery equipped with the ANF@MOFs separator has a high first-cycle
discharge capacity of 1081.92 mAh g–1 and a prolonged
cycling performance with a capacity of 876.36 mAh g–1 at 0.5 C after 200 cycles. As a result, the high-performance ANF@MOFs
composite separator provides significant potential for future lithium–sulfur
batteries.