Effective One-Step Preparation of High Performance Positive and Negative Composite Electrodes for All-Solid-State Li2S-Si Batteries

Abstract

All-solid-state lithium sulfur batteries provide higher theoretical energy density and safety performance than commercial lithium ion batteries. Combining a Li2S positive electrode with a Si-negative electrode is particularly attractive because it avoids highly reactive lithium metal. In general, the positive and negative composite electrodes are prepared by several time-consuming preparation processes. This study reports an effective one-step preparation process in which the high-performance positive and negative composite electrodes are reacted by mechanical milling of the electrode active materials, conductive carbons, and raw materials of solid electrolyte. This process simultaneously generates the solid electrolyte and a composite of electrode active materials, solid electrolyte, and carbon in the composite electrodes. Moreover, the specific surface area of carbon accelerated the generation of solid electrolyte and the compounding of the electrode active materials. The charge–discharge performances of both the Li2S positive and Si-negative composite electrodes were boosted by the high specific surface area of carbon. Furthermore, a full-battery cell using the Li2S positive and Si-negative composite electrodes achieved a high area capacity of 4.2 mAh cm−2 and an energy density of 376 Wh kg−1(masses of the positive and negative composite electrodes) at 0.25 mA cm−2 and 25 °C.