Wu Zeyi, Lu Chengjie, Wang Yanan, Zhang Lin, Jiang Le, Tian Wenchao, Cai Cailing, Gu Qinfen, Sun Zhengming, Hu Linfeng
Department of Materials Science, Fudan University, Shanghai, 200433, P. R. China.
School of Materials Science and Engineering, Southeast University, Nanjing, 211189, P. R. China.
Small. 2020 Sep;16(35):e2000698. doi: 10.1002/smll.202000698. Epub 2020 Aug 9.
The realizing of high-performance rechargeable aqueous zinc-ion batteries (ZIBs) with high energy density and long cycling life is promising but still challenging due to the lack of suitable layered cathode materials. The work reports the excellent zinc-ion storage performance as-observed in few-layered ultrathin VSe nanosheets with a two-step Zn intercalation/de-intercalation mechanism verified by ex situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) characterizations. The VSe nanosheets exhibit a discharge plateau at 1.0-0.7 V, a specific capacity of 131.8 mAh g (at 0.1 A g ), and a high energy density of 107.3 Wh kg (at a power density of 81.2 W kg ). More importantly, outstanding cycle stability (capacity retention of 80.8% after 500 cycles) without any activation process is achieved. Such a prominent cyclic stability should be attributed to its fast Zn diffusion kinetics (D ≈ 10 cm s ) and robust structural/crystalline stability. Density functional theory (DFT) calculation further reveals a strong metallic characteristic and optimal zinc-ion diffusion pathway with a hopping energy barrier of 0.91 eV. The present finding implies that 2D ultrathin VSe is a very promising cathode material in ZIBs with remarkable battery performance superior to other layered transitional metal dichalcogenides.
实现具有高能量密度和长循环寿命的高性能可充电水系锌离子电池（ZIBs）前景广阔，但由于缺乏合适的层状阴极材料，仍然具有挑战性。这项工作报告了在少层超薄VSe纳米片中观察到的优异锌离子存储性能，通过非原位X射线衍射（XRD）和X射线光电子能谱（XPS）表征验证了两步锌嵌入/脱嵌机制。VSe纳米片在1.0 - 0.7 V处表现出放电平台，在0.1 A g时比容量为131.8 mAh g，在功率密度为81.2 W kg时能量密度高达107.3 Wh kg。更重要的是，在没有任何活化过程的情况下实现了出色的循环稳定性（500次循环后容量保持率为80.8%）。这种突出的循环稳定性应归因于其快速的锌扩散动力学（D≈10 cm s）和强大的结构/晶体稳定性。密度泛函理论（DFT）计算进一步揭示了强金属特性和最佳锌离子扩散途径，跳跃能垒为0.91 eV。目前的发现表明，二维超薄VSe是ZIBs中一种非常有前途的阴极材料，其电池性能显著优于其他层状过渡金属二硫属化物。
