In-situ TEM observation of fast and stable reaction of lithium polysulfide infiltrated carbon composite and its application as a lithium sulfur battery electrode for improved cycle lifetime

Lithium sulfur batteries (LSB) are attracting attention as a next generation energy storage device because of their high energy density, low cost, and environmental friendliness surpassing that of lithium ion batteries (LIBs). An in-situ transmission electron microscopy experiment performed in this work revealed a fast electrochemical reaction and minimum volume changes during lithiation and delithiation for lithium polysulfide infiltrated vat black particles. Based on this observation, we developed a simple and cost-effective method for the lithium polysulfide battery to achieve high performance by employing a nanostructured vat black/carbon cloth electrode that exhibits high electrical conductivity, good mechanical properties, and a high surface area. These benefits enabled a high sulfur loading mass, captured the lithium polysulfide intermediate reaction products, and avoided structural changes. As a result, high specific discharge capacity of 1300 mAhg(-1) at 0.2 C, an outstanding rate performance (846 mAhg 1 at 2 C) and an areal capacity of up to 3.352 mAhcm(-2) with a sulfur loading mass of 3.8 mg were achieved. Increasing the sulfur loading mass to 7 mg (areal capacity of up to 4.24 mAhcm(-2)) still resulted in a desirable discharge capacity of 928 mAhg(-1). This work provides a promising path towards practical lithium sulfur batteries.