α-MnO2 nanowires:: A catalyst for the O2 electrode in rechargeable lithium batteries
α-MnO2 nanowires:: A catalyst for the O2 electrode in rechargeable lithium batteries
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DOI：
10.1002/anie.200705648
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发表时间：
2008-01-01
影响因子：
16.6
通讯作者：
Bruce, Peter G.
中科院分区：
文献类型：
--
作者：
Debart, Aurelie;Paterson, Allan J.;Bruce, Peter G.
可充电锂电池中的电荷存储受到正极的限制，通常是锂嵌入化合物LiCoO 2，其可以存储130 mAhg Ω 1。[1-3]世界范围内正在进行激烈的努力，以发现新的锂嵌入化合物用作正电极，希望其可以提供约300 mA hg-f1的比容量。然而，将容量显著增加到超过该极限是一个重大挑战，需要更激进的方法，例如用O2电极代替嵌入电极，其中来自电解质的Li+和来自外部电路的E2在含有催化剂的多孔基质内与来自空气的O2可逆地联合收割机。[4-8]虽然它提供了比嵌入电极更高的容量，但在进一步考虑用于技术应用之前，需要进行许多基础工作来理解和优化锂电池的O2电极的性能。催化剂的性质起着关键作用。在专注于其他任务之前，如减少催化剂负载和优化孔隙率，粘合剂和电解质，确定用于电极反应的良好催化剂非常重要。在这里，我们表明，α-MnO 2纳米线给出了最高的电荷存储容量尚未报告这样的电极，达到3000毫安时每克碳，或505毫安时，如果归一化的总电极质量。此外，通过避免深度放电，已经证明了优异的容量保持率。最后，比较了氧电极和传统插层化合物的容量。可逆氧电极示意图见图1。在放电时，Li+离子（电解质）和电解质（外部电路）与O2（空气）联合收割机结合以在多孔碳电极的孔内形成Li 2 O2。[4-8]先前，我们证明了Li/O2电池的可再充电性涉及Li 2 O2分解回Li和O2。[8]我们早期对可充电Li/O2电池的研究集中在电解二氧化锰（EMD）作为氧电极中的催化剂。[8]最近，我们研究了许多其他潜在的催化剂材料，包括Co 3 O 4、Fe 2 O3、CuO和CoFe 2 O 4。[9]这样的研究用于证明催化剂的性质是控制催化剂活性的关键因素。
Charge storage in rechargeable lithium batteries is limited by the positive electrode, usually the lithium intercalation compound LiCoO2, which can store 130 mAhgÀ1.[1–3] Intense efforts are underway worldwide to discover new lithium intercalation compounds for use as positive electrodes which, it is hoped, may deliver specific capacities of about 300 mA hg À1. However, increasing the capacity significantly beyond this limit is a major challenge requiring a more radical approach, such as replacement of the intercalation electrode by an O2 electrode, in which Li+ from the electrolyte and eÀ from the external circuit combine reversibly with O2 from the air within a porous matrix containing a catalyst.[4–8] Although it provides higher capacities than intercalation electrodes, much fundamental work is required to understand and optimize the performance of the O2 electrode for lithium batteries before it can be considered further for technological application. The nature of the catalyst plays a key role. It is important to identify good catalysts for the electrode reaction before focusing on other tasks, such as reducing the catalyst loading and optimizing porosity, binder, and electrolyte. Herein we show that a-MnO2 nanowires give the highest charge storage capacity yet reported for such an electrode, reaching 3000 mAh per gram of carbon, or 505 mAhgÀ1 if normalized by the total electrode mass. Furthermore, by avoiding deep discharge, excellent capacity retention has been demonstrated. Finally, the capacities delivered by an O2 electrode and a conventional intercalation compound are compared.The reversible oxygen electrode is shown schematically in Figure1. On discharge, the Li+ ions (electrolyte) and eÀ (external circuit) combine with O2(air) to form Li2O2 within the pores of the porous carbon electrode.[4–8] Previously, we demonstrated that rechargeability of the Li/O2 cell involves decomposition of Li2O2 back to Li and O2.[8] Our earlier studies on the rechargeable Li/O2 cell focused on electrolytic manganese dioxide (EMD) as catalyst in the oxygen electrode.[8] Recently, we examined a number of other potential catalyst materials including Co3O4, Fe2O3, CuO, and CoFe2O4.[9] Such investigations served to demonstrate that the nature of the catalyst is a key factor controlling the