Investigation of the effect of anion/cation-modified cellulose nanofibers/MXene composite aerogels on the high-performance lithium-sulfur batteries.

Renewable natural polymer: cellulose nanofibers (CNF), with the characteristics of one-dimensional nanowires structure and rich in functional groups, have shown a wide range of potential applications in lithium-sulfur batteries. However, the electrical insulating properties of CNF inhibit its application in host materials of lithium-sulfur batteries. In this work, the influence of the CNF with different charge states (positively or negatively charged CNF) and delaminated-MXene (d-MXene) composite materials on the electrochemical performance of lithium-sulfur batteries was investigated. Two different types of cellulose nanofibers (TEMPO-mediated oxidation cellulose nanofiber and cationic cellulose nanofiber) were combined with d-MXene through the directional assembly of ice templates to prepare d-MXene/TEMPO-mediated oxidation cellulose nanofiber (MT) and d-MXene/cationic cellulose nanofiber (MC) composite aerogels, respectively. As a result, MT-4 aerogel as the cathode for lithium-sulfur battery shows excellent rate performance (capacity of 848.1 mA h g⁻¹ at the current density of 2 C), MC-6 aerogel cathode exhibits ultra-high capacity (1573.7 mA h g⁻¹ at 0.1 C), and excellent long-term cycling performance (capacity retention rate of 96.3% after 200 cycles). The design strategy of renewable cellulose nanofiber composite materials offers a new angle for the design of low-cost and high-performance lithium-sulfur batteries. [ABSTRACT FROM AUTHOR]