Zinc-ion batteries are emerging as next-generation rechargeable batteries that can operate in aqueous electrolytes. We first examine the feasibility of open-structured VO 2 (B) as a Zn 2+ intercalation host. A bond-valence sum energy map predicts that four Zn 2+ -ion sites (Zn C , Zn A1 , Zn A2 , and Zn C′ ) can exist in the structure. Using first-principles calculations, we verified that 0.5 mol of Zn 2+ ions can be reversibly (de)intercalated with an average voltage of ∼0.61 V (vs Zn 2+ /Zn), which is comparable with the experimental results. The specific capacity of VO 2 (B) at 50 mA g −1 is maintained up to ∼365 mAh g −1 corresponding to the storage capacity of ∼0.57 mol of Zn 2+ ions in the framework of VO 2 (B), and its redox reaction occurs at ∼0.61 V. The high capacity is maintained for 200 cycles, with capacity retention of 80% (288 mAh g −1 ). Moreover, the capacity delivered by the VO 2 (B) electrode is stable even with cycling at a rate of 5C (1750 mA g −1 ) at approximately 110 mAh g −1 . This high-power capability of VO 2 is supported by the theoretical approach based on first-principles calculation, which shows the activation barrier for Zn 2+ diffusion in the VO 2 (B) structure. These findings demonstrate the potential of open-structured VO 2 (B) as a new candidate material.

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A Macro Fiber Composite (MFC) is a piezoelectric fiber composite which has an interdigitated electrode, rectangular cross-section and unidirectional polycrystalline piezoceramic (PZT) fibers embedded in the polymer matrix. A MFC actuator has much higher actuation performance and flexibility than a monolithic piezoceramic actuator. Moreover, the single crystal piezoelectric material exhibits much higher induced strain levels, energy density and coupling than those of polycrystalline piezoceramic materials. Thus, the performance of an MFC can be improved by using single crystal piezoelectric fiber instead of polycrystalline piezoceramic fiber. This study investigates the analytical modeling, material properties and actuation performance of an MFC using single crystal piezoelectric material (single crystal MFC). For single crystal MFC, the mechanical properties are calculated by the classical lamination theory, and the uniform fields model (UFM) is adopted to predict piezoelectric strain constants. In addition, the actuation performance of the single crystal MFC with the active twist rotor blade is studied. The material properties and actuation performance of single crystal MFC are compared with those of standard MFC.

C/NVMP allowed high electrochemical performance supported by the replace V by the Mn promoted the easier electron transfer through lower band gap energy than Mn-free NVP and carbon coating increase the electric conductivity up to 2 × 10−3 s cm−1, which led to superior electrode performance.