Polysulfide and Li Dendrite-Blocking Aramid Nanofiber/Metal–Organic Framework Composite Separators for Advanced Lithium–Sulfur Batteries

Abstract

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.

Nickel–Nitrogen–Carbon Nanoparticles as Polysulfide Adjustment Layers for Lithium–Sulfur Batteries

“…This finding demonstrates the rapid conversion of LPSs at low redox potential. 30,31 To investigate the influence of aluminum foil, N−C, and Ni−N−C on LPS redox kinetics, symmetric cells were assembled and subjected to CV measurements at 5 mV s −1 within a voltage window of −0.8 to +0.8 V, as illustrated in Figure 7b. It is noteworthy that the current density of the aluminum foil can be neglected, suggesting its limited catalytic effect on the conversion of LPSs.…”

Ti3C2Tx nanosheet@Cu/Fe-MOF separators for high-performance lithium–sulfur batteries: an experimental and density functional theory study

“…Functional groups on the separator have been investigated recently to enhance the electrochemical performance and utilization of sulfur intermediates. 21,22…”

“…Functional groups on the separator have been investigated recently to enhance the electrochemical performance and utilization of sulfur intermediates. 21,22 Herein, we suggest novel coatings on glass fiber separators to satisfy all high-performance Li-S battery requirements. A conductive Ti 3 C 2 T x (MXene) nanosheet/Fe-MOF or Ti 3 C 2 T x (MXene) nanosheet/Cu-MOF layer with a thickness of 500 nm was coated on the glass fiber separator to act as a trapping layer (Fig.…”

Solution Blow Spinning of the Benzimidazole-Containing Aramid Nanofibers for Separators of Lithium-Ion Batteries

“…Although electrospinning can be applied, , the method is still challenging in mass production with controllable cost and high efficiency, and the porous skeletons stacked simply by electrospun nanofibers tend to show poorer mechanical strength and toughness than the microporous polyolefin or their ceramic composites . The breakthrough on para -aramid nanofibers (ANFs) by the deprotonation of Kevlar fibers in the DMSO/KOH system presents an opportunity for the preparation of para -aramid separators. − The ANF membranes inherit the remarkable performance of Kevlar. The issue is that ANF-based separators tend to have a dense structure because of the strong intermolecular hydrogen bonding .…”