Affordable High-performance Sulfur Positive Composite Electrode for All-solid-state Li-S Batteries Prepared by One-step Mechanical Milling without Solid Electrolyte or Li₂S

Abstract

All-solid-state lithium–sulfur batteries are excellent candidates for next-generation batteries due to their high energy density, safety, and affordability. However, the current fabrication process faces challenges related to processing steps and the high cost of raw materials. In this study, we provide a highly effective and affordable one-step method for fabricating sulfur-positive composite electrodes in a short processing time using low-cost materials. High-performance positive electrodes were prepared by mechanical milling using sulfur, high-surface-area carbon, P₂S₅, and lithium oxoacid salt or oxide such as Li₂CO₃, or Li₂O for 2 h. The resulting sulfur-positive composite electrodes showed capacities of over 1600 and 1200 mAh g⁻¹(S) (7.6 and 5.7 mAh cm⁻²) at 0.25 and 3.2 mA cm⁻² at 25 °C, respectively. The high performance is attributed to the simultaneous production of an ionic conductive material through the reaction of P₂S₅ with lithium oxoacid salts or oxide and the formation of a sulfur composite. A full battery cell comprising this positive electrode and Li-Si alloy negative electrode exhibits an energy density of 700 Wh kg⁻¹ (based on positive and negative composite electrodes) and an area capacity of 8.4 mAh cm⁻² at 0.25 mA cm⁻² and 25 °C.