High Performance Sulfur-Composite Cathode for Lithium-Ion Sulfur Batteries

Abstract

Rapid development of portable electronics, electric transport and renewable energy demands for high performance rechargeable batteries. Conventional lithium-ion batteries with intercalation cathodes have limited energy density and expensive. Lithium sulfur (Li/S) battery is an attractive alternative due to a higher theoretical capacity and energy density of 1672 mAh g-1 and 2600 Wh kg-1, respectively [1]. Sulphur is a promising cathode because of its abundance, low-cost and environmentally friendliness as well compared with commercial transition-metal cathodes. However, practical application of Li/S batteries is hindered by several drawbacks: use of dangerous lithium-metal anode, electrical-insulating nature of sulfur causing its low utilization; solubility of lithium polysulfides formed in the electrode process leading to severe capacity fading and low coulombic efficiency. Numerous attempts have been made to overcome these disadvantages by mixing sulfur with conducting agents such as carbonaceous materials and/or conductive polymers, which allows for enhanced utilization of sulfur and capacity per unit mass of sulfur [2-3]. In this work a Sulfur/Polyacrylonitrile/Ketjen Black ternary composite electrode (S/PAN/KB) was prepared and examined as a cathode for Li-ion/S battery coupled with prelithiated graphite anode (Li-Gr) in Li-Gr | Electrolyte| S/PAN/KB cell. The partially pyrolyzed and cyclized PAN stabilizes sulfur and suppresses its dissolution into electrolyte [4]. Formation of a homogeneous hierarchical mesoporous structure in S/PAN/KB was observed by SEM, EDS mapping and XRD techniques. The cell with this composite cathode delivered a reversible discharge capacity of 600 mAh g-1 of composite (1450 mAh g−1 of S) at 0.2 C, and retained about 85% of this value over 200 cycles. Even at high cycling rates up to 1 C, the cell demonstrated a good rate capability, delivering a highly reversible discharge capacity of 750 mAh g−1, which was superior to the performance of a Li-metal anode half-cell counterpart. Using this cell, the batteries of different size were assembled (Fig. a) and tested; the battery stack exhibited stable cycling performance (Fig. b). Further details of this work will be presented at the Meeting.