Tunable Pseudocapacitive Intercalation of Chloroaluminate Anions into Graphite Electrodes for Rechargeable Aluminum Batteries
Tunable Pseudocapacitive Intercalation of Chloroaluminate Anions into Graphite Electrodes for Rechargeable Aluminum Batteries
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DOI：
10.1149/1945-7111/ac0648
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发表时间：
2021-06
影响因子：
3.9
通讯作者：
Jeffrey H. Xu;T. Schoetz;Joseph R. McManus;V. Subramanian;Peter W. Fields;R. Messinger
中科院分区：
文献类型：
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作者：
Jeffrey H. Xu;T. Schoetz;Joseph R. McManus;V. Subramanian;Peter W. Fields;R. Messinger
使用含氯铝酸盐电解质的可再充电铝-石墨电池一直是重要研究的焦点，特别是由于其高倍率能力。工程石墨电极已被证明具有超级电容器般的倍率性能，尽管它们通过多原子AlCl 4−阴离子的电化学嵌入来存储电荷。然而，这种速率能力的起源并不清楚。在这里，使用电化学技术，我们定量地解开了扩散限制的法拉第，赝电容和电容对电荷存储的贡献，揭示了AlCl 4−阴离子由于低离子扩散限制而具有显着的赝电容特性。原始的和轻度剥离的石墨进行比较，剥离导致显着更高的赝电容AlCl 4−嵌入在最高电位的氧化还原对，以及更高的恒电流容量保持在更快的放电速率。石墨结构，离子质量传输，和电化学AlCl 4−嵌入的总速率之间的关系进行了讨论。多孔电极的电解质相内的离子扩散被示出在控制在较高的电势和更快的速率下的嵌入速率中起关键作用，这可以通过减少电极弯曲度来增强。结果表明，氯铝酸阴离子嵌入石墨表现出非扩散限制的赝电容贡献，通过修改石墨结构可调。
Rechargeable aluminum-graphite batteries using chloroaluminate-containing electrolytes have been the focus of significant research, particularly due to their high-rate capabilities. Engineered graphite electrodes have been shown to exhibit supercapacitor-like rate performance, despite the fact they store charge via the electrochemical intercalation of polyatomic AlCl 4− anions. However, the origins of such rate capabilities are not well understood. Here, using electrochemical techniques, we disentangle quantitatively the diffusion-limited Faradaic, pseudocapacitive, and capacitive contributions to charge storage, revealing that AlCl 4− anions intercalate into graphite with significant pseudocapacitive characteristics due to low ion diffusion limitations. Pristine and mildly exfoliated graphites are compared, where exfoliation resulted in significantly higher pseudocapacitive AlCl 4− intercalation at the highest potential redox pair as well as higher galvanostatic capacity retention at faster discharge rates. The relationships between graphite structure, ion mass transport, and the overall rate of electrochemical AlCl 4− intercalation are discussed. Ion diffusion within the electrolyte phase of the porous electrode is shown to play a key role in controlling the rate of intercalation at higher potentials and faster rates, which can be enhanced by reducing electrode tortuosity. The results establish that chloroaluminate anion intercalation into graphite exhibits non-diffusion-limited pseudocapacitive contributions that are tunable by modifying the graphite structure.