Improved electrochemical performances of sulfur-microporous carbon composite electrode for Li/S battery

摘要

A sulfur-microporous (S-MIP) carbon composite was prepared for use as a cathode for rechargeable Li/S batteries. Two sulfur-embedded methods, S-impregnation (IS) and S-liquefied pore filling (LS), were applied for the preparation of the S-MIP carbon composites. The pristine elemental S of the polycrystalline a-S_8 undergoes a structural change to an amorphous-S (a-S) structure in the S-MIP carbon composite created by the IS method. During sulfur loading of 40-50 wt %, the S-MIP carbon composite created by the IS method showed a BET SSA value of around 500 m~2 g~(-1) and a pore volume of 0.2 cm~3 g~(-1). However, after the LS process was applied to the S-MIP carbon composite, at 160 ℃ and 10 h, the a-S structure in the S-MIP carbon composite became recrystalline a-S_8. Little remained of the porosity in the S-MIP carbon composite prepared by the LS method due to the large portion of the S crystalline phase. The best discharge capacity was obtained with an S-MIP carbon composite created by the IS method, with the result of 680 mA h g~(-1) after 50 cycles at 0.1 ℃, i.e., *47 % higher than that by the LS method.