Metal–Organic Frameworks/Conducting Polymer Hydrogel Integrated Three-Dimensional Free-Standing Monoliths as Ultrahigh Loading Li–S Battery Electrodes

Abstract

The lithium−sulfur (Li−S) system is a promising material for the nextgeneration of high energy density batteries with application extending from electrical vehicles to portable devices and aeronautics. Despite progress, the energy density of current Li−S technologies is still below that of conventional intercalation-type cathode materials due to limited stability and utilization efficiency at high sulfur loading. Here, we present a conducting polymer hydrogel integrated highly performing free-standing three-dimensional (3D) monolithic electrode architecture for Li−S batteries with superior electrochemical stability and energy density. The electrode layout consists of a highly conductive three-dimensional network of N,P codoped carbon with welldispersed metal−organic framework nanodomains of ZIF-67 and HKUST-1. The hierarchical monolithic 3D carbon networks provide an excellent environment for charge and electrolyte transport as well as mechanical and chemical stability. The electrically integrated MOF nanodomains significantly enhance the sulfur loading and retention capabilities by inhibiting the release of lithium polysulfide specificities as well as improving the charge transfer efficiency at the electrolyte interface. Our optimal 3D carbon-HKUST-1 electrode architecture achieves a very high areal capacity of >16 mAh cm −2 and volumetric capacity (C V ) of 1230.8 mAh cm −3 with capacity retention of 82% at 0.2C for over 300 cycles, providing an attractive candidate material for future high-energy density Li−S batteries.

Host Materials Anchoring Polysulfides in Li–S Batteries Reviewed

“…Liu et al presented a 3D free‐standing monolithic electrode comprising ZIF‐67 and HKUST‐1 well dispersed in highly conductive N, P codoped carbon. [ 359 ] The 3D monolithic carbon network enabled the encapsulation and electrical correlation of MOF nanodomains, which were responsible for prolonged capacity retention of sulfur species and increased sulfur loading. An optimized 3D carbon‐HKUST‐1 cathode achieved high areal and volume capacities of 16 mAh cm −2 and 1231 mAh cm −3 at 0.2 C, respectively.…”

Two‐Dimensional Transition Metal Carbides and Nitrides (MXenes): Synthesis, Properties, and Electrochemical Energy Storage Applications

“…Compared to conventional LIBs, rechargeable Li‐S batteries have a great potential for the next generation power sources since they are able to provide higher energy density at a lower cost and better environmental benignity . The theoretical energy density of Li‐S battery reaches 2600 Wh kg −1 on a weight basis, which is 3–5 times higher than that of the most advanced commercial LIBs .…”

Recent advances in nanomaterials for high-performance Li–S batteries

“…Carbanaceous 3D hybrid nanomaterials often combine 1D and 2D nanomaterials to create specialized nanoarchitectures for preventing polysulfide dissolution. These materials may contain combinations of CNTs, graphene, carbon nanofibers, activated porous carbon, and polymeric carbon materials to create nanoarchitectures of differing porosity, intimate sulfur-carbon contact, high sulfur loading capabilities, and chemical and mechanical stability [25][26][27] .…”