Unusual Li-Storage Behaviour of Two-Dimensional ReS2 Single Crystals

Unusual Li-storage properties are observed for two-dimensional ReS2 compared to its analogue MoS2. First, we prepared ReS2 single crystals (99.9% crystallinity) by chemical vapour transport with high yield and utmost purity. Li-storage properties are assessed using a standard half-cell assembly with metallic Li as the counter electrode. The highly crystalline ReS2 rendered excellent electrochemical characteristics with interesting features. This logically leads to further exploration of ReS2 towards Li-storage. Indeed, ReS2 could act as efficient intercalation host for Li-ions with lower redox potential (similar to 1.2 V vs. Li) and decent reversibility (similar to 0.4 mol Li). On the other hand, high reversibility is registered while deep discharging of the active material. This eventually obeys the perfect conversion pathway. Interestingly, electrochemically activated ReS2 also rendered good reversibility and eventually serves as an insertion host with a working potential of similar to 2 V vs. Li.