Enhanced Cyclic Stability of Sulfur Electrode by a Li‐Nafion‐Supported Encapsulated Configuration

Abstract

Lithium–sulfur batteries are deemed to have the opportunity to replace lithium‐ion batteries because of their high energy density. Nonetheless, the shuttling of soluble long‐chain polysulfides severely deteriorates the cyclic performances of the batteries. Herein, an encapsulated sulfur electrode to tackle the shuttle effect is designed. This high‐performance electrode is fabricated by encapsulating the active sulfur inside a sealing configuration composed of lithiated Nafion (Li‐Nafion), carbon black (BP2000), and a binder of polytetrafluoroethylene. The dense surface of the encapsulated configuration can physically obstruct the mobility of soluble polysulfides. Meanwhile, the sulfonic acid groups fixed on the Li‐Nafion backbone provide a robust electrostatic repulsion to inhibit the negatively charged polysulfides from migrating into the electrolyte. Therefore, the encapsulated sulfur electrode delivers 522.6 mAh g−1 at the 600th cycle with a retention of 80.36%, exhibiting a more competitive cyclic stability than the pristine sulfur electrode.

Enhancing the Cycle Performance of Lithium‐Sulfur Batteries by Coating the Separator with a Cation‐Selective Polymer Layer

“…[11][12][13][14][15][16][17][18][19][20][21][22][23] Our previous studies have systematically probed the impact of the coverage percentage of the interlayer on the sulfur electrode. [24,25] These investigations demonstrated that the cyclic stability of the battery would be enhanced as the coverage percentage rose.…”

“…It is widely verified that the pathway through which soluble polysulfides migrate to the anode can be extremely obstructed by an interlayer, thus remarkably reducing the shuttle effect [11–23] . Our previous studies have systematically probed the impact of the coverage percentage of the interlayer on the sulfur electrode [24,25] . These investigations demonstrated that the cyclic stability of the battery would be enhanced as the coverage percentage rose.…”

Carbonate swollen lithiated Nafion electrolyte for quasi-solid-state lithium–sulfur batteries

“…Several studies demonstrated the improvement of LSB performance by exploiting Li-Nafion as a coating layer on standard polymer separators, 30 or cast over positive 31,32 or negative electrodes, 33 as a free-standing membrane 34–37 and as a constituent of the composite positive electrodes. 34 Li-Nafion is typically used in LSBs once swollen in low boiling point ether mixtures of 1,3-dioxolane (DOL) and 1,2-dimethoxyethane (DME) to improve adhesion and reduce interfacial resistances.…”

“…29 Aer ion exchange of H + with Li + , the lithiated Naon (Li-Naon) membrane swollen with specic organic solvents possesses an ionic conductivity of 4 × 10 −4 S cm −1 at room temperature, 26 which is much larger than that of many previously reported monoionically conductive polymer electrolytes. Several studies demonstrated the improvement of LSB performance by exploiting Li-Naon as a coating layer on standard polymer separators, 30 or cast over positive 31,32 or negative electrodes, 33 as a free-standing membrane [34][35][36][37] and as a constituent of the composite positive electrodes. 34 Li-Naon is typically used in LSBs once swollen in low boiling point ether mixtures of 1,3-dioxolane (DOL) and 1,2-dimethoxyethane (DME) to improve adhesion and reduce interfacial resistances.…”