Abstract
Pseudocapacitive charge storage has been regarded as a promising mechanism to achieve both high specific energy and power energy storage devices. Some pseudocapacitive anode materials show great high-rate performance, however, it remains a significant challenge to develop the cathode ones. Herein, for the first time, we report a layered iron vanadate (Fe5V15O39(OH)9⋅9H2O, named as kazakhstanite) nanosheets (FeVO NSs) with featuring ultrathin layer thickness (< 10 nm). The FeVO NSs are synthesized by a facile wet-chemical approach with a high yield. Compared to the FeVO nanoparticles, the crystalline layered FeVO NSs have additional interlayered Li+ storage sites, leading to the enhanced capacity. Ex-situ X-ray diffraction results demonstrate a non-phase change process and there is only ~ 1.1% layer expansion/shrinkage during lithiation and delithiation process. Based on detail kinetics analysis and ex-situ X-ray photoelectron spectroscopy results, it is found that over 70% of total capacity is pseudocapacitive contribution, which contributes to the ultrahigh-rate capability (a high capacity of 350, 273 and 90 mAh g−1 is achieved at 0.1, 1 and 20 A g−1, respectively) and excellent cycling stability over thousands of cycles. This work presents the high performance vanadate material that delivers highly pseudocapacitive behavior, and provides a promising direction to realize both high energy and high power lithium storage.
Layered iron vanadate nanosheets are synthesized by a facile wet-chemical approach with a high yield. The layered iron vanadate nanosheets cathode exhibits pseudocapacitive behavior with a non-phase change process and deliver remarkable high capacity, ultrahigh rate capability and cycling stability for lithium storage. [Display omitted]
•Layered iron vanadate nanosheets are synthesized by a facile wet-chemical method with high yield.•Iron vanadate nanosheets cathode shows excellent high rate capability and cycling stability.•The layered iron vanadate cathode delivers pseudocapacitive lithium storage mechanism.•Pseudocapacitive cathodes exhibit great potentials for high-rate lithium storage.