Wang Guoqing, Tu Fangfang, Xie Jian, Du Gaohui, Zhang Shichao, Cao Gaoshao, Zhao Xinbing
State Key Laboratory of Silicon Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310027 P. R. China.
State Key Laboratory of Silicon Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310027 P. R. China; Key Laboratory of Advanced Materials and Applicationsfor Batteries of Zhejiang Province Hangzhou 310027 P. R. China.
Adv Sci (Weinh). 2016 Apr 28;3(10):1500339. doi: 10.1002/advs.201500339. eCollection 2016 Oct.
The working of nonaqueous Li-O batteries relies on the reversible formation/decomposition of LiO which is electrically insulating and reactive with carbon and electrolyte. Realizing controlled growth of LiO is a prerequisite for high performance of Li-O batteries. In this work, a sandwich-structured catalytic cathode is designed: graphene/Au-nanoparticles/Au-nanosheets (G/Au-NP/Au-NS) that enables controlled growth of LiO spatially and structurally. It is found that thin-layer LiO (below 10 nm) can grow conformally on the surface of Au NPs confined in between graphene and Au NSs. This unique crystalline behavior of LiO effectively relieves or defers the electrode deactivation with LiO accumulation and largely reduces the contact of LiO with graphene and electrolyte. As a result, Li-O batteries with the G/Au-NP/Au-NS cathode exhibit superior electrochemical performance. A stable cycling of battery can last 300 times at 400 mA g when the capacity is limited at 500 mAh g. This work provides a practical design of catalytic cathodes capable of controlling LiO growth.
非水锂氧电池的工作依赖于LiO的可逆形成/分解，LiO是电绝缘的，并且会与碳和电解质发生反应。实现LiO的可控生长是高性能锂氧电池的前提条件。在这项工作中，设计了一种三明治结构的催化阴极：石墨烯/金纳米颗粒/金纳米片（G/Au-NP/Au-NS），它能够在空间和结构上实现LiO的可控生长。研究发现，薄层LiO（低于10纳米）可以在限制于石墨烯和金纳米片之间的金纳米颗粒表面上保形生长。LiO的这种独特晶体行为有效地缓解或延缓了因LiO积累导致的电极失活，并大大减少了LiO与石墨烯和电解质的接触。结果，具有G/Au-NP/Au-NS阴极的锂氧电池表现出优异的电化学性能。当容量限制在500 mAh g时，电池在400 mA g下可以稳定循环300次。这项工作提供了一种能够控制LiO生长的催化阴极的实用设计。
