Lithium-Ion Intercalation into Graphite in SO2-Based Inorganic Electrolyte toward High-Rate-Capable and Safe Lithium-Ion Batteries

Herein, we have identified that lithium ions in an SO₂-based inorganic electrolyte reversibly intercalate and deintercalate into/out of graphite electrode using ex situ X-ray diffraction and various electrochemical methods. X-ray photoelectron spectroscopy shows that the solid electrolyte interphase on the graphite electrode is mainly composed of inorganic compounds, such as LiCl and lithium sulfur-oxy compounds. Graphite electrode in SO₂-based inorganic electrolyte has stable capacity retention up to 100 cycles and outstanding rate capability performance. This can be attributed to low interfacial impedance and high ionic conductivity of SO₂-based inorganic electrolyte, which are superior to those of conventional organic electrolytes. Considering the remarkable rate capability and intrinsically nonflammable properties of the electrolyte, use of graphite and an SO₂ electrolyte will likely facilitate the development of advanced lithium-ion batteries.