Stabilizing high sulfur loading Li-S batteries by chemisorption of polysulfide on three-dimensional current collector

The large volume change during cycles, extreme low electronic/ionic conductivity of sulfur and lithium sulfide, and high solubility of high-order polysulfide (PS) in electrolyte are three major barriers for practical applications of Li-S batteries. Current strategy to migrate these three issues is to physically and/or chemically encapsulate the sulfur into porous carbon host (PCH), which is only suitable for a low S loading cathode. The large volume change during charge-discharge process especially in a thicker electrode with high areal S loading will detach the carbon/Li2S particles apart from each other, resulting in fast capacity decay. Although incorporation of large amount of S into 3D carbon paper (CP) can maintain the electrode integration, it cannot effectively immobilize soluble PS. In this work, we chemically bond the PS to both doped PCH and 3D doped CP current collector to suppress the shuttle reaction of PS, and also maintain the electronic/ionic connection during prolonged cycles. The S, N doped CP/doped PCH/S cathode with high areal sulfur loading of 9.0 mg cm(-2) provide a high capacity of 1013 mA h g(-1) with a slow capacity fading rate of 0.074% per cycle for 300 cycles, presenting one of the best cycling stability at the similar S loading reported to date. Moreover, systematic investigations demonstrated that chemical bonding of PS to CP current collector can more effectively enhance the cycling stability of high sulfur loading cathode, compared to the current method by chemical bonding of PS to PCH. This sulfur cathode by filling a large amount of S/C composites into functionalized CP matrix bring a new and promising direction to realization of high energy lithium-sulfur batteries.