A high cycling stability of dual‐ion batteries is greatly challenging, as the size required for inserting anions matches only insufficiently with the interlayer spacing of graphite which is often used as positive electrode. Herein, an activated expanded graphite (AEG) electrode is successfully prepared via KOH treatment. The loose structure of AEG accommodates the volume expansion caused by anion intercalation, and the large specific surface area facilitates the immersion of electrolyte ions to afford more energy density. Thus, the cycling stability is largely enhanced without losing capacity. Matching with activated carbon as negative electrode and an ionic liquid electrolyte, the assembled dual‐ion battery achieves an energy density of 43 Wh kg⁻¹ at the power density of 756 W kg⁻¹ within a working window of 0–3.6 V. Specifically, the energy density retains 83 % after 50 cycles. Such effective and low‐cost electrode optimization opens up a new route toward full enhancement on the cycling performance of positive electrodes for dual‐ion batteries.

中文翻译：

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碳基双离子电池，具有增强的容量和循环稳定性

双离子电池的高循环稳定性极富挑战性，因为插入阴离子所需的尺寸仅与经常用作正极的石墨的层间间距匹配得不够。在此，通过KOH处理成功地制备了活性膨胀石墨（AEG）电极。AEG的松散结构可适应因阴离子嵌入而引起的体积膨胀，并且较大的比表面积可促进电解质离子的浸没，从而提供更多的能量密度。因此，在不损失容量的情况下大大提高了循环稳定性。组合的双离子电池与作为负极的活性炭和离子液体电解质相匹配，在756 W kg ^-1的功率密度下实现了43 Wh kg ^-1的能量密度。在0-3.6 V的工作窗口内。具体地说，在50个循环后，能量密度保持83％。这种有效且低成本的电极优化为全面增强双离子电池正极的循环性能开辟了一条新途径。