Long cycle performance folium cycas biochar/S composite material for lithium-sulfur batteries

Biomass has rich porous texture and unique physical and chemical properties, so it is widely used to enhance the electrochemical performances of lithium-sulfur batteries. In this paper, porous biochar is fabricated by easily obtained folium cycas. Acetic acid (HAc) is used to clean the ash content in cavity and solve the problem of pore blockage. The results showed that the folium cycas biochar (FCB) treated with HAc increased the specific surface area by 44.7% (2954 m2/g) and the cumulative pore volume by 67.5% (1.39 cm3/g). The FCB has rich nano-scale meso/microporous tubular pores which provide a natural high-efficiency space for sulfur storage and buffer the volume expansion, so that the prepared composite cathode material of FCB/S has a first discharge capacity of up to 1317 mAh/g and stable at 910 mAh/g after 5 cycles. The capacity can still reach 790 mAh/g after 200 cycles with an attenuation rate of only 0.068% for each cycle.