Band Diagram and Rate Analysis of Thin Film Spinel LiMn2O4 Formed by Electrochemical Conversion of ALD‐Grown MnO
Band Diagram and Rate Analysis of Thin Film Spinel LiMn2O4 Formed by Electrochemical Conversion of ALD‐Grown MnO
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DOI：
10.1002/adfm.201602773
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发表时间：
2016-11
影响因子：
19
通讯作者：
M. Young;Hans-Dieter Schnabel;A. Holder;S. George;C. Musgrave
中科院分区：
文献类型：
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作者：
M. Young;Hans-Dieter Schnabel;A. Holder;S. George;C. Musgrave
纳米级尖晶石锂锰氧化物作为用于先进电池技术以及其他电化学应用的高倍率阴极材料而受到关注。在这项工作中，证明了通过原子层沉积（ALD）生长的MnO的室温电化学转化来合成厚度在20和200 nm之间的尖晶石锂锰氧化物（LiMn 2 O 4）的氧化物膜。研究了LiMn 2 O 4薄膜在含有Li+、Na+、K+和Mg 2+的电解液中的电荷存储性能。通过筛选混合密度泛函理论计算获得的LiMn 2 O 4的统一电化学带图（UEB）分析也用于扩展对LiMn 2 O 4中电荷存储和稳定性基础的现有理解。结果表明，将Li+或其他阳离子掺入到主体二氧化锰尖晶石结构（λ-MnO 2）中稳定了来自导带的电子态，其与LiMn 2 O 4的已知氧化还原电位一致。此外，循环伏安法实验表明，LiMn 2 O 4高达30%的容量来自不需要补偿阳离子质量传输的体电荷切换。本文描述的混合ALD电化学合成，UEB分析和独特的电荷存储机制提供了一个基本框架，以指导未来用于离子掺入电荷存储的纳米级电极材料的开发。
Nanoscale spinel lithium manganese oxide is of interest as a high‐rate cathode material for advanced battery technologies among other electrochemical applications. In this work, the synthesis of ultrathin films of spinel lithium manganese oxide (LiMn2O4) between 20 and 200 nm in thickness by room‐temperature electrochemical conversion of MnO grown by atomic layer deposition (ALD) is demonstrated. The charge storage properties of LiMn2O4 thin films in electrolytes containing Li+, Na+, K+, and Mg2+ are investigated. A unified electrochemical band‐diagram (UEB) analysis of LiMn2O4 informed by screened hybrid density functional theory calculations is also employed to expand on existing understanding of the underpinnings of charge storage and stability in LiMn2O4. It is shown that the incorporation of Li+ or other cations into the host manganese dioxide spinel structure (λ‐MnO2) stabilizes electronic states from the conduction band which align with the known redox potentials of LiMn2O4. Furthermore, the cyclic voltammetry experiments demonstrate that up to 30% of the capacity of LiMn2O4 arises from bulk electronic charge‐switching which does not require compensating cation mass transport. The hybrid ALD‐electrochemical synthesis, UEB analysis, and unique charge storage mechanism described here provide a fundamental framework to guide the development of future nanoscale electrode materials for ion‐incorporation charge storage.