CaV6O16 center dot 2.8H(2)O with Ca2+ Pillar and Water Lubrication as a High-Rate and Long-Life Cathode Material for Ca-Ion Batteries

Due to the low cost and low redox potential of calcium, calcium ion batteries (CIBs) are considered a competitive candidate for large-scale energy storage systems and have attracted increasing attention in recent years. However, the development of CIBs is still in its infancy and hindered by the lack of high-performance cathode materials. Herein, the metahewettite layered vanadium oxide with the Ca2+ pillar and water lubrication is reported as a cathode material for CIBs. Benefiting from the large interlayer spacing, pillar, and water lubrication effect, the as-prepared CaV6O16 center dot 2.8H(2)O (CVO) delivers a high discharge capacity of 175.2 mAh g(-1) at 50 degrees C and 131.7 mAh g(-1) at room temperature, a long cycle life of 1000 cycles and the highest rate performance (up to 1000 mA g(-1)) in organic electrolyte. Furthermore, a single-phase Ca2+ insertion and extraction reaction is revealed by in situ X-ray diffraction and in-situ Fourier transform infrared spectroscopy. Density functional theory computations indicate that Ca2+ tends to diffuse along the b direction with a low energy barrier of 0.36 eV in CVO. This work is bringing the performance of cathode materials for CIBs to a higher level and of great significance for accelerating the development of CIBs.