All-MXene-Based Integrated Electrode Constructed by Ti3C2 Nanoribbon Framework Host and Nanosheet Interlayer for High-Energy-Density Li-S Batteries.

High-energy-density lithium-sulfur (Li-S) batteries hold promise for next-generation portable electronic devices, but are facing great challenges in rational construction of high-performance flexible electrodes and innovative cell configurations for actual applications. Here we demonstrated an all-MXene-based flexible and integrated sulfur cathode, enabled by three-dimensional alkalized Ti3C2 MXene nanoribbon (a-Ti3C2 MNR) frameworks as a S/polysulfides host (a-Ti3C2-S) and two-dimensional delaminated Ti3C2 MXene (d-Ti3C2) nanosheets as interlayer on a polypropylene (PP) separator, for high-energy and long-cycle Li-S batteries. Notably, an a-Ti3C2 MNR framework with open interconnected macropores and an exposed surface area guarantees high S loading and fast ionic diffusion for prompt lithiation/delithiation kinetics, and the 2D d-Ti3C2 MXene interlayer remarkably prevents the shuttle effect of lithium polysulfides via both chemical absorption and physical blocking. As a result, the integrated a-Ti3C2-S/d-Ti3C2/PP electrode was directly used for Li-S batteries, without the requirement of a metal current collector, and exhibited a high reversible capacity of 1062 mAh g-1 at 0.2 C and enhanced capacity of 632 mAh g-1 after 50 cycles at 0.5 C, outperforming the a-Ti3C2-S/PP electrode (547 mAh g-1) and conventional a-Ti3C2-S on an Al current collector (a-Ti3C2-S/Al) (597 mAh g-1). Furthermore, the all-MXene-based integrated cathode displayed outstanding rate capacity of 288 mAh g-1 at 10 C and long-life cyclability. Therefore, this proposed strategy of constructing an all-MXene-based cathode can be readily extended to assemble a large number of MXene-derived materials, from a group of 60+ MAX phases, for applications such as various batteries and supercapacitors.