Pre-Lithiation Method with Span-CNT Cathode in Li-S Batteries

Abstract

Lithium-sulfur (Li-S) batteries with a theoretical specific energy density up to 2,600 Wh·kg-1 is regarded as one of the most promising energy chemical power systems. However, the development of Li-S batteries still faces numerous technical challenges. Both sulfur and Li2S is electrically insulating, leading to a low power capability; the polysulfide generated during charging and discharging processes is highly soluble in electrolytes, resulting in loss of active material and severe redox shuttle effect. To address above issues, sulfurized polyacrylonitrile (SPAN) has been developed as a novel composite cathode material. The strong bonding between sulfur and polyacrylonitrile enables SPAN cathode to operate in commercial carbonate-based electrolyte with an exceptional cycle ability, inhibiting the shuttle effect and self-discharge phenomenon observed in conventional Li-S batteries. In this study, a freestanding SPAN/CNT composite is developed as the cathode material for Li-S batteries, which is capable to deliver a high specific capacity of 1303 mAh g-1 at 0.2 C and a desirable high-rate performance of 1085 mAh g-1 at 2.0 C. Furthermore, Li-ion sulfur full batteries based on SPAN/CNT cathode and graphite anode was assembled using pre-lithiation method. Both the cathode and anode pre-lithiation method was investigated for optimization of system performance. With a high specific capacity and good cycle life, the proposed Li-ion sulfur full battery system provides an alternative approach to fabricate safe and low cost metal-free Li-ion batteries.