Au‐Decorated Cracked Carbon Tube Arrays as Binder‐Free Catalytic Cathode Enabling Guided Li2O2 Inner Growth for High‐Performance Li‐O2 Batteries
Au‐Decorated Cracked Carbon Tube Arrays as Binder‐Free Catalytic Cathode Enabling Guided Li2O2 Inner Growth for High‐Performance Li‐O2 Batteries
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DOI：
10.1002/adfm.201603088
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发表时间：
2016-11
影响因子：
19
通讯作者：
Fangfang Tu;Junping Hu;Jian Xie;G. Cao;Shichao Zhang;Shengyuan A. Yang;Xinbing Zhao;H. Yang
中科院分区：
文献类型：
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作者：
Fangfang Tu;Junping Hu;Jian Xie;G. Cao;Shichao Zhang;Shengyuan A. Yang;Xinbing Zhao;H. Yang
由于其极高的能量密度，Li-O2电池在最近的研究中获得了越来越多的关注。然而，已知放电产物的沉积（绝缘Li 2 O2）严重限制Li-O2电池的电化学性能。虽然广泛的研究集中在通过控制Li 2 O2生长来缓解电极失活，但没有提供永久或有效的机制。在这里，提出了一种独特的设计，包括由内壁上装饰有Au纳米颗粒的开裂碳亚微米管（CST）阵列构成的催化阴极。Au纳米颗粒的引入不仅提高了电极导电性，还提供了催化位点，引导薄层Li 2 O2在开裂的CST内共形生长。密度泛函理论计算支持CST上的Au装饰有利于Li 2 O2在内管壁上的共形生长。Li 2 O2的这种生长行为使得Li 2 O2容易分解，防止碳管电极完全、快速失活，并保留反应物传输的自由空间。具有Au@CST的Li-O2电池表现出良好的倍率性能（在1000 mA g-1的高电流密度下为1208 mAh g-1）和长循环寿命（在400 mA g-1的电流密度下为112次循环，具有500 mAh g-1的有限容量）。
Owing to their extremely high energy density, Li‐O2 batteries have attained increasing attention in recent studies. However, deposition of the discharge product, insulating Li2O2, is known to seriously limit the electrochemical performance of Li‐O2 batteries. While extensive studies have focused on relieving electrode deactivation by controlling Li2O2 growth, no permanent or effective mechanism is delivered. Here, a unique design comprising a catalytic cathode constructed by cracked carbon submicron tube (CST) arrays decorated with Au nanoparticles on inner walls is proposed. The introduction of Au nanoparticles not only improves electrode conductivity but also provides catalytic sites, guiding conformal growth of thin‐layered Li2O2 inside the cracked CST. Density functional theory calculations support that Au decoration on CST favors the conformal growth of Li2O2 on inner tubular walls. This growth behavior of Li2O2 renders easy decomposition of Li2O2, prevents carbon tube electrode from full, rapid deactivation, and preserves the free space for reactants transport. Li‐O2 cells with Au@CST exhibit good rate capability (1208 mAh g–1 at a high current density of 1000 mA g–1) and long cycle life (112 cycles at a current density of 400 mA g–1 with a limited capacity of 500 mAh g–1).