Construction of NiCoO2-(Ni,Co)Se2 hybrid nanorods as an effective bifunctional interlayer for lithium‑sulfur batteries

Abstract

The practical application of lithium‑sulfur (Li[sbnd]S) batteries is hindered by the shuttle effect caused by the dissolution of polysulfides in the electrolyte during the charge-discharge process, and the sluggish kinetic conversion of polysulfides. In this work, we present a novel hybrid material, nanorod-shaped NiCoO2-(Ni,Co)Se2 hybrid (NCOSe), synthesized through simple hydrothermal and further selenization methods. These NCOSe hybrid nanorods were uniformly coated onto a commercial polypropylene (PP) separator via vacuum filtration for application in Li[sbnd]S batteries. In the hybrid structure, the NiCoO2 nanorod component exhibits strong polysulfides adsorption due to its high polarity, while (Ni,Co)Se2 part promotes favorable polysulfides conversion due to superb catalytic conversion properties. Electrochemical testing reveals that the Li[sbnd]S full cell with the bifunctional NCOSe/PP separator delivers an initial specific capacity of 1277 mAh g−1 at a current density of 0.1C (1C = 1675 mA g−1). After 200 cycles at 0.2C, the specific capacity reaches 793 mAh g−1, with a low average capacity decay of just 0.123 % per cycle. With a higher sulfur loading of 3.0 mg cm−2, the cell achieves a specific capacity of 455 mAh g−1 after 220 cycles at 0.5C, and with a maximum sulfur loading of 4.4 mg cm−2 at 0.5C, it still maintains 72 % (311 mAh g−1) of its initial capacity after 400 cycles. This study introduces a novel hybrid material with dual functionalities-enhanced polysulfides adsorption and accelerated polysulfides conversion, offering improved cycling stability of Li[sbnd]S batteries. © 2025 Elsevier Ltd