Manipulating Li2S2/Li2S mixed discharge products of all-solid-state lithium sulfur batteries for improved cycle life

All-solid-state lithium-sulfur batteries offer a compelling opportunity for next-generation energy storage, due to their high theoretical energy density, low cost, and improved safety. However, their widespread adoption is hindered by an inadequate understanding of their discharge products. Using X-ray absorption spectroscopy and time-of-flight secondary ion mass spectrometry, we reveal that the discharge product of all-solid-state lithium-sulfur batteries is not solely composed of Li2S, but rather consists of a mixture of Li2S and Li2S2. Employing this insight, we propose an integrated strategy that: (1) manipulates the lower cutoff potential to promote a Li2S2-dominant discharge product and (2) incorporates a trace amount of solid-state catalyst (LiI) into the S composite electrode. This approach leads to all-solid-state cells with a Li-In alloy negative electrode that deliver a reversible capacity of 979.6 mAh g-1 for 1500 cycles at 2.0 A g-1 at 25 degrees C. Our findings provide crucial insights into the discharge products of all-solid-state lithium-sulfur batteries and may offer a feasible approach to enhance their overall performance.

Automated summary

All-solid-state lithium-sulfur batteries have the potential to be the next-generation energy storage solution due to their high theoretical energy density, low cost, and improved safety. However, the lack of understanding of their discharge products has hindered their widespread adoption. Through the use of advanced analytical techniques, it has been revealed that the discharge product of these batteries is not solely composed of Li2S but rather a mixture of Li2S and Li2S2. This finding has led to the proposal of an integrated strategy to improve the overall performance of these batteries.