Uncovering the Binder Interactions with S-PAN and MXene for Room Temperature Na-S Batteries.

Wong, Andrew Jun Yao; Lieu, Wei Ying; Chinnadurai, Deviprasath; Ng, Man-Fai; Seh, Zhi Wei · Nano Lett · 2023

basic_science · Level V

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Abstract

MXenes and sulfurized polyacrylonitrile (S-PAN) are emerging as possible contenders to resolve the polysulfide dissolution and volumetric expansion issues in sodium-sulfur batteries. Herein, we explore the interactions between Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXenes and S-PAN with traditional binders such as polyvinylidene difluoride (PVDF), poly(acrylic acid) (PAA), and carboxymethyl cellulose (CMC) in Na-S batteries for the first time. We hypothesize that the linearity and polarity of the binder significantly influence the dispersion of S-PAN over Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>. The three-dimensional polar CMC binder resulted in better contact surface area with both S-PAN and Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>. Moreover, the improved binding of the discharge products with the CMC binder effectively traps them and prevents unwanted shuttling. Consequently, the Na-S battery using the CMC binder displayed a high initial capacity of 1282 mAh/g<sub>(s)</sub> at 0.2 C and a low capacity fading of 0.092% per cycle over 300 cycles. This work highlights the importance of understanding MXene-binder interactions in sulfur cathodes.