Greatly Improved Conductivity of Double-Chain Polymer Network Binder for High Sulfur Loading Lithium–Sulfur Batteries with a Low Electrolyte/Sulfur Ratio

Binders have been considered to play a key role in realizing high-energy-density lithium–sulfur batteries. However, the accompanying problems of limited conductivity and inferior affinity of soluble polysulfide intermediates bring down their comprehensive performance for practical applications. Herein, the synthesis of a novel double-chain polymer network (DCP) binder by polymerizing 4,4′-biphenyldisulfonic acid connected pyrrole monomer onto viscous sodium carboxymethyl cellulose matrix, yielding a primary crystal structure is reported. Consequently, the resulted binder enables superior rate performance from 0.2 C (1326.9 mAh g−1) to 4 C (701.4 mAh g−1). Moreover, a high sulfur loading of 9.8 mg cm−2 and a low electrolyte/sulfur ratio (5:1, µL mg−1) are achieved, exhibiting a high area capacity of 9.2 mAh cm−2. In situ X-ray diffraction analysis is conducted to monitor the structural modifications of the cathode, confirming the occurrence of sulfur reduction/recrystallization during charge–discharge process. In addition, in situ UV–vis measurements demonstrate that DCP binder impedes the polysulfide migration, thereby giving rise to high capacity retention for 400 cycles.

Duke Scholars

Author Jie Liu Chemistry