Lithium ion electrochemical insertion in vanadium pentoxide/cucurbit[6]uril intercalates

Abstract

Cucurbit[6]uril (CB[6]) and its complex with VO²⁺ (CB[6]VO) were intercalated into lamellar vanadium pentoxide in several proportions, generating a series of hybrid pillarised intercalates in the form of xerogel films. These different guests dramatically affect Li⁺ insertion/expulsion from the composites during redox processes. Our results show that CB[6] has little effect or may even impair charge compensation by Li⁺, while CB[6]VO exerts the opposite effect, enhancing this process when compared to pure vanadium pentoxide. This is clear evidence that CB[6] binds these ions retaining them in the bulk structure, and when the oculi are blocked by VO²⁺ ions, the macrocycle acts as a non-coordinating pillar in the structure favoring ion traffic, and charge compensation processes become easier. Specific charge capacities for pure vanadium pentoxide, CB[6] and CB[6]VO intercalates correspond to 158, 168 and 230 mA h g⁻¹ respectively.