Arginine modification of hybrid cobalt/nitrogen Ti3C2Tx MXene and its application as a sulfur host for lithium-sulfur batteries

Abstract

The shuttling effect of lithium polysulfides (LiPSs) is one of the challenges facing the commercialization, which leads to a significant capacity degradation. This paper proposes a novel method to promote polysulfide transformation by employing arginine to regulate the layer spacing of cobalt-nitrogen doped Ti3C2Tx MXene (Co-N@Ti3C2Tx-Arg). The results revealed that arginine effectively extended the interlayer spacing and promoted the homogeneous dispersion of Co and N atoms, thus endowing the sulfur host with a high catalytic activity during the charging and discharging processes. The extended interlayer spacing increased the specific surface area and captured sufficient LiPSs for subsequent catalytic conversions, while the Co and N doping on the surface of Ti3C2Tx significantly promoted the rapid conversion of the LiPSs to Li2S. Therefore, the S cathode coated with Co-N@Ti3C2Tx-Arg exhibited an excellent cycling stability with a low-capacity fading rate of 0.083% over 200 cycles in addition to a high reversible capacity of 1,365.4 mAh g-1 at 0.1 C.