MXene based self-assembled cathode and antifouling separator for high-rate and dendrite-inhibited Li–S battery

Highlights: • A self-assembly strategy to prepare interlinked Mxene and PEI for high loading cathode. • A separator with ultrafast ion conductivity and antifouling property. • A dual chemisorption mechanism to boost the low order polysulfide conversion. • The integrated Li–S battery showing reliable capacity (800 mAh g⁻¹) at nearly 10 mAh cm⁻². -- Abstract: We demonstrate a novel strategy to enhance sulfur loading and rate performance for Li–S battery by synchronously coupling a nanostructured cathode with an antifouling separator via a facile electrostatic self-assembly approach. The assembly of two dimensional (2D) MXene and positively charged 1D CNT-Polyethyleneimine was observed to controllably address the key issues of sluggish ionic transport, and produce an integrate cathode with dynamic crosslinking network. Moreover, an antifouling separator is proposed by this strategy for the first time, which features well-organized inter-lamellar porosity, dual polarity and high conductivity. The antifouling separator is found to play a pivotal role in: 1) low-order polysulfide activation, 2) high rate cyclability, and 3) Li dendrites inhibition. Our integrated design realizes a long-term capacity of 980 mAh g⁻¹ at 5 mA cm⁻² over 500 cycles (sulfur loading: 2.6 mg cm⁻²). Furthermore, a flexible self-assembled cathode with high loading (5.8 mg cm⁻²) and superb mechanical strength (13 MPa), demonstrates an appealing areal capacity of 7.1 mAh cm⁻² and rate performance at nearly 10 mA cm⁻².