Department of Chemistry, ‡Artie McFerrin Department of Chemical Engineering, and §Department of Materials Science and Engineering, Texas A&M University , College Station, Texas 77843, United States.
Langmuir. 2017 Jun 20;33(24):5975-5981. doi: 10.1021/acs.langmuir.6b04163. Epub 2017 Jun 12.
Crystalline vanadium pentoxide (VO) has attracted significant interest as a potential cathode material for energy storage applications due to its high theoretical capacity. Unfortunately, the material suffers from low conductivity as well as slow lithium ion diffusion, both of which affect how fast the electrode can be charged/discharged and how many times it can be cycled. Colloidal crystal templating (CCT) provides a simple approach to create well-organized 3-D nanostructures of materials, resulting in a significant increase in surface area that can lead to marked improvements in electrochemical performance. Here, a single layer of open shell VO architectures ca. 1 μm in height with ca. 100 nm wall thickness was fabricated using CCT, and the electrochemical properties of these assemblies were evaluated. A decrease in polarization effects, resulting from the higher surface area mesostructured features, was found to produce significantly enhanced electrochemical performance. The discharge capacity of an unpatterned thin film of VO (∼8.1 μAh/cm) was found to increase to ∼10.2 μAh/cm when the material was patterned by CCT, affording enhanced charge storage capabilities as well as a decrease in the irreversible degradation during charge-discharge cycling. This work demonstrates the importance of creating mesoscale electrode surfaces for improving the performance of energy storage devices and provides fundamental understanding of the means to improve device performance.
五氧化二钒（VO）晶体由于其理论比容量高，作为储能应用的潜在阴极材料引起了人们的极大兴趣。不幸的是，该材料的导电性和锂离子扩散速度都很慢，这两者都会影响电极的充电/放电速度以及可以循环的次数。胶体晶体模板（CCT）提供了一种简单的方法来制造具有良好组织的 3-D 纳米结构材料，从而显著增加表面积，这可以显著提高电化学性能。在这里，使用 CCT 制造了单层开口壳 VO 结构，高度约为 1μm，壁厚约为 100nm，并评估了这些组件的电化学性能。发现较高的表面积介孔结构特征降低了极化效应，从而产生了显著增强的电化学性能。当材料通过 CCT 进行图案化时，未图案化的 VO 薄膜（约 8.1μAh/cm）的放电容量增加到约 10.2μAh/cm，从而提供了增强的电荷存储能力以及在充放电循环过程中不可逆降解的减少。这项工作证明了为提高储能设备的性能而创建介观电极表面的重要性，并为提高器件性能的方法提供了基本的理解。
