Boosted Charge-Transfer behavior for ultrafast Zn storage by constructing intrinsic heterojunction of ammonium vanadate nanoribbons coupling with interlaminar MXenes nanosheets

Ammonium vanadate (NH4V4O10, NHVO) is one of the most promising cathode materials for aqueous zinc-ion batteries (ZIBs) owing to its inherent large interplanar spacing, highly reversible electrochemical reaction mechanism and admirable specific capacity. However, the fragile interlayer structure and sluggish electron transport behavior generally cause tardy electrochemical reaction kinetics and result in poor cycling stability and rate capabilities. In this work, a novel intrinsic heterojunction cathode (NHVO@MX) of NHVO nanoribbons coupling with inserted Mxenes (MX) nanosheets is rationally constructed on a flexible carbon cloth substrate for wearable ZIB applications. The intercalated MX nanosheets not only serve as the spacer to isolate the NHVO interlayers as well as efficiently accelerate electron and ion transport behaviors, hence preserving the numerous exposed active areas required for rich and rapid Zn storage. Most impressively, it presents the lowest charge-transfer barrier among all the reported vanadate-based materials induced by the interlaminar MX nanosheets, demonstrated by both experimental measurement and theoretical calculation. As a result, the as-prepared heterojunction cathode delivers high specific capacity of 437 mAh·g−1, excellent rate capability and ultralong cycling life (over 2000 cycles). Therefore, manufacturing the heterojunction laminar cathode with incorporated MX can be considered a prospective strategy for next-generation advanced ZIBs.