Self-discharge of lithium–sulfur cells using stainless-steel current-collectors

Abstract

The self-discharge behaviour of Li–S cell, is investigated through changes in the open-circuit voltage (OCV) and discharge capacity with storage time. A fresh Li–S cell experiences 72% sulfur utilization during the first discharge, as based on the theoretical capacity for the formation of Li 2S. After 30 days of storage, the OCV has fallen from 2.48 to 2.16 V and the discharge capacity has decreased from 1206 to 924 mAh g −1 (based on sulfur). Analysis of the self-discharged sample by a variety of techniques shows the formation of lithium polysulfides, such as Li 2S n ( n ≥ 1) from the reaction of lithium and sulfur, which is related to the corrosion of the stainless current-collector. Stainless steel is not the most appropriate current-collector material for Li–S cells. The extent of self-discharge can be decreased by using a gold-coated current-collector that offers protection against corrosion.