Achieving Low Overpotential Li鈥揙2 Battery Operations by Li2O2 Decomposition through One-Electron Processes

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• 作者：Jin Xie ; Qi Dong ; Ian Madden ; Xiahui Yao ; Qingmei Cheng ; Paul Dornath ; Wei Fan ; Dunwei Wang
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：December 9, 2015
• 年：2015
• 卷：15
• 期：12
• 页码：8371-8376
• 全文大小：369K
• ISSN：1530-6992

文摘

As a promising high-capacity energy storage technology, Li鈥揙₂ batteries face two critical challenges, poor cycle lifetime and low round-trip efficiencies, both of which are connected to the high overpotentials. The problem is particularly acute during recharge, where the reactions typically follow two-electron mechanisms that are inherently slow. Here we present a strategy that can significantly reduce recharge overpotentials. Our approach seeks to promote Li₂O₂ decomposition by one-electron processes, and the key is to stabilize the important intermediate of superoxide species. With the introduction of a highly polarizing electrolyte, we observe that recharge processes are successfully switched from a two-electron pathway to a single-electron one. While a similar one-electron route has been reported for the discharge processes, it has rarely been described for recharge except for the initial stage due to the poor mobilities of surface bound superoxide ions (O₂^{鈥?/sup>), a necessary intermediate for the mechanism. Key to our observation is the solvation of O₂鈥?/sup> by an ionic liquid electrolyte (PYR₁₄TFSI). Recharge overpotentials as low as 0.19 V at 100 mA/g_carbon are measured.}