Siloxane based copolymer sulfur as binder-free cathode for advances lithium-sulfur batteries

One of the reasons why lithium-sulfur batteries have not yet been commercialized is a great attenuation of the capacity, although their theoretical capacity is ultrahigh. To alleviate this problem, we developed multifunctional organic matter, 3-aminopropyltriethoxysilane (APS), for preparing a uniform hybrid consists of silica 3D network skeleton and copolymerized sulfur nanoparticles (cpS). In this hybrid, abundant amidogen in APS induced polymerization with sulfur, which formed uniform copolymerized sulfur nanoparticles (nano sulfur), restraining the shuttle effect of polysulfides. Meanwhile, polycondensation APS not only acted as an efficiently binder, affording compact cathodes, but also formed a stable 3D silica structure to encapsulate sulfur nanoparticles, relieving the volume change of sulfur. Consequently, this binder-free cpS composite exhibited much enhanced electrochemical performances, including a high capacity of 1187.8 mAh·g^-1 at 0.1 C and a low capacity fading of 0.0654% per cycle for 500 cycles at 1 C. This study paved the way for high-energy-density batteries by simply applying a low-cost, environmentally-friendly, powerful network polymer cathode material.