有序大孔电池电极材料在高充放电倍率下的局限性
Limitations of Ordered Macroporous Battery Electrode Materials at High Charge and Discharge Rates
摘要：
向电池电极增加孔隙率被认为普遍适用于增加空间以适应体积膨胀、电解质进入所有活性材料、帮助减轻较厚电极的不良C-速率性能以及允许用其他材料填充。有序多孔电极，例如具有大孔隙度的反蛋白石，已经是一种模型系统：不含粘合剂和导电添加剂，电互连，限定的孔隙度和孔径随厚度变化，良好的电解质润湿性以及在正常速率下在半电池和Li电池中令人惊讶的良好电极性能。我们表明，固有的电子电导率是重要的，并在快速的本征电导率最终抑制任何电荷存储在电极材料。在富液式锂电池三电极电池中使用反蛋白石V2 O 5的模型系统，其锂电化学非常好地理解，我们表明，超过10 C，电极几乎不能存储电荷，但一旦降低到< 1C，则完全恢复。我们展示了IO材料如何使用X射线衍射，拉曼散射和电子显微镜在锂化下进行改性，并且在较高的速率下很少或没有反应发生在材料上。我们还使用计时电流法来检查速率行为，并将高速率性能和完全容量抑制的限制与IO网络的固有面外电导率联系起来。数据表明，即使是具有纳米级尺寸、功能性孔隙率和完全材料互连性的理想化电极，当它们即使在完全被电解质浸泡时也导电性较低时，其高倍率性能也受到根本限制。虽然添加所谓的功能尺寸减小、孔隙率等对于某些材料可能是有用的，但这些潜在的益处显然对于锂离子电池中的高倍率电极并不普遍有用。
英文摘要：
Adding porosity to battery electrodes is believed to be universally useful for adding space to accommodate volumetric expansion, electrolyte access to all active materials, helping to mitigate poor C-rate performance for thicker electrodes and for allowing infilling with other materials. Ordered porous electrode, such as inverse opals that have macroporosity, have been a model system: binder and conductive additive free, interconnected electrically, defined porosity and pore size with thickness, good electrolyte wettability and surprisingly good electrode performance in half cells and Li-battery cells at normal rates. We show that the intrinsic electronic conductivity is important, and at fast rates the intrinsic conductivity ultimately suppresses any charge storage in electrode materials. Using a model system of inverse opal V2O5in a flooded Li battery three-electrode cell, whose Li electrochemistry is very well understood, we show that beyond 10 C, electrodes can store almost no charge, but completely recover once reduced to < 1C. We show how the IO material is modified under lithiation using X-ray diffraction, Raman scattering and electron microscopy, and that little or no reaction occurs to the material at higher rates. We also use chronoamperometry to examine rate behaviour and link the limitations in high rate performance, and complete capacity suppression, to the intrinsic out-of-plane conductivity of the IO network. The data show that even idealized electrodes with nanoscale dimensions, functional porosity and full material interconnectivity, are fundamentally limited for high rate performance when they are less conductive even when fully soaked with electrolyte. While adding so-called functional size reduction, porosity etc. can be useful for some materials, these potential benefits are clearly not universally useful for high rate electrodes in Li-ion batteries.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
