High-density charge (energy) storage under supercapacitive mode requires an electrode that would deliver larger space for charge accumulation and offer a larger electrochemical potential difference at an electrode–electrolyte interface. Porous carbon has been a preferred electrode for commercial supercapacitors; however, its charge storability is much lower than that of state-of-the-art charge-storage devices such as lithium-ion batteries. We show that one of the primary limiting factors is the voids in porous carbon, which do not contribute to the capacitance because their sizes are much larger than the size of the solvated/unsolvated ions in the electrolyte. We partially activate these voids by filling them with a flower-shaped 3D hierarchical pseudocapacitive material (MnCo₂O₄) by assuming that flower-shaped fillers would provide an additional easily accessible surface for charge adsorption. Less than 10 wt % MnCo₂O₄ in the porous carbon from palm kernel shells through simple wet impregnation results in a five-fold increase in the charge storability. Laboratory prototypes of symmetric supercapacitors are fabricated using the MnCo₂O₄-filled carbon electrodes, which show five times higher specific energy than pure carbon and are cycled over 5000 times with >95% capacitance retention. The present strategy of activating the voids by hierarchical 3D nanostructures could be applied to build high-performance energy-storage devices.

中文翻译：

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用于高密度超电容电荷存储的多孔碳中的空隙空间控制

在超级电容模式下的高密度电荷（能量）存储需要一个电极，该电极将为电荷积累提供更大的空间，并在电极与电解质的界面处提供更大的电化学电势差。多孔碳已成为商用超级电容器的首选电极；但是，它的电荷存储能力远低于最新的电荷存储设备（如锂离子电池）。我们表明，主要的限制因素之一是多孔碳中的空隙，它们对电容没有贡献，因为它们的尺寸比电解质中溶剂化/未溶剂化离子的尺寸大得多。我们通过用花形3D分层伪电容材料（MnCo ₂ O ₄），假设花朵形的填充物会为电荷吸附提供另一个易于访问的表面。通过简单的湿浸渍，来自棕榈仁壳的多孔碳中少于10 wt％的MnCo ₂ O ₄导致电荷存储能力提高了五倍。对称超级电容器的实验室原型是使用MnCo ₂ O ₄填充的碳电极制造的，该电极显示出的比能是纯碳的五倍，并且循环使用5000次以上，电容保持率> 95％。通过分层3D纳米结构激活空隙的当前策略可以应用于构建高性能的能量存储设备。