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

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 3 C 2 T x 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 3 C 2 T x . The threedimensional polar CMC binder resulted in better contact surface area with both S-PAN and Ti 3 C 2 T x . 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 (s) 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.

A Critical Review on Room‐Temperature Sodium‐Sulfur Batteries: From Research Advances to Practical Perspectives

“…As presented in Table 3, the state-of-the-art reports on various host materials for the S cathodes of RT-Na/S batteries have been systematically summarized. A wide variety of porous host materials have been reported for S cathodes, including carbonaceous materials (C), [163,170,180] covalent S/C composites, [183,184] metal single atoms modified C (M SA /C), [47,196,[199][200][201] metal nanocrystals modified C (M/C), [170,214] metal oxide modified C (M x O y /C), [217,221] metal sulfide-modified C (M x S y /C), [224][225][226] MXenes, [235] and other non-carbonaceous materials (None-C). [193,194] Similar to the choice of host materials for Na metal anodes, carbonaceous-based composite materials have been widely investigated as host materials for S cathodes as a result of their high electrical conductivity, low material weight, and easily tunable porous structures.…”

High-Performance Sulfurized Polyacrylonitrile Cathode by Using MXene as a Conductive and Catalytic Binder for Room-Temperature Na/S Batteries

“…The covalent bonding between sulfur and the backbone derived from PAN can eliminate the shuttle effect of dissolved polysulfides by the solid–solid reaction mechanism. − However, insufficient electronic/ionic conductivity of PAN@S material causes low electrochemical activity, slow reaction kinetics, and inferior rate capability and prevents full realization of its theoretical capacity and cycling stability. The methods of nanostructure construction, ,, ion doping, , and combination with conductive matrix , have been proposed to tackle this issue. For example, Ahn et al prepared a flexible cathode consisting of PAN@S nanofibers for fast ion transport, which exhibited a capacity of 342 mAh g –1 –PAN@S at 0.1 C. Xie et al prepared a Se-doped PAN@S with the Se element distributed at the molecular level, which showed much improved conductivity and kinetics with a capacity of ∼541 mAh g –1 –PAN@Se0.08S0.92 at 0.1 A g –1 .…”

“…have been widely studied in energy storage field due to their unique 2D structure, metallic conductivity, excellent hydrophilicity and mechanical properties. − Especially in Li/S and Na/S batteries, MXenes have been confirmed to be effective in improving the electronic conductivity, , adsorbing the dissolved polysulfides, and facilitating the conversion kinetics of the polysulfides . Recently, Seh et al prepared a PAN@S/MXene composite via a freeze-drying method and assembled into the electrode with sodium carboxymethyl cellulose (CMC) as a binder, which displayed the capacities of ∼571 and ∼262 mAh g –1 –PAN@S at 0.2 and 4 C, respectively. Although some progress has been made, most of the reported PAN@S electrodes focus on material modification with complicated preparation processes, and the performance, especially the rate capability, still has a great deal of room to be improved.…”

Direct Observation of the Evolutionary Process in Room-Temperature Sodium–Sulfur/Selenium Batteries Using operando Light Microscopy

“…Developing technologies for large-scale and long-term energy storage is crucial. Room-temperature sodium–sulfur/selenium (RT Na–S/Se) batteries are attractive due to their abundant raw material resources and high energy density. − Due to its high electronegativity, elemental sulfur can accept two valence electrons during reduction, thus having a high specific capacity. However, the inherent low electrical conductivity of sulfur hinders its use as an electrode material (5 × 10 –30 S cm –1 ) .…”