Li Ying, Raghavan Rahul, Wagner Nicholas A, Davidowski Stephen K, Baggetto Loïc, Zhao Ran, Cheng Qian, Yarger Jeffery L, Veith Gabriel M, Ellis-Terrell Carol, Miller Michael A, Chan Kwai S, Chan Candace K
Materials Science and Engineering School for Engineering of Matter Transport and Energy Arizona State University Tempe AZ 85287 USA.
Department of Chemistry and Biochemistry Arizona State University Tempe AZ 85287 USA.
Adv Sci (Weinh). 2015 May 5;2(6):1500057. doi: 10.1002/advs.201500057. eCollection 2015 Jun.
Silicon clathrates contain cage-like structures that can encapsulate various guest atoms or molecules. An electrochemical evaluation of type I silicon clathrates based on BaAl Si as the anode material for lithium-ion batteries is presented here. Postcycling characterization with nuclear magnetic resonance and X-ray diffraction shows no discernible structural or volume changes even after electrochemical insertion of 44 Li (≈1 Li/Si) into the clathrate structure. The observed properties are in stark contrast with lithiation of other silicon anodes, which become amorphous and suffer from large volume changes. The electrochemical reactions are proposed to occur as single phase reactions at approximately 0.2 and 0.4 V versus Li/Li during lithiation and delithiation, respectively, distinct from diamond cubic or amorphous silicon anodes. Reversible capacities as high as 499 mAh g- at a 5 mA g rate were observed for silicon clathrate with composition BaAlSi, corresponding to ≈1.18 Li/Si. These results show that silicon clathrates could be promising durable anodes for lithium-ion batteries.
硅包合物含有笼状结构，能够包封各种客体原子或分子。本文介绍了基于BaAlSi的I型硅包合物作为锂离子电池负极材料的电化学评估。即使在向包合物结构中电化学插入44个锂原子（≈1个锂原子/硅原子）之后，通过核磁共振和X射线衍射进行的循环后表征也未显示出明显的结构或体积变化。观察到的这些特性与其他硅负极的锂化情况形成鲜明对比，其他硅负极会变成非晶态并经历较大的体积变化。据推测，在锂化和脱锂过程中，电化学反应分别在相对于Li/Li约0.2 V和0.4 V时以单相反应发生，这与金刚石立方或非晶硅负极不同。对于组成为BaAlSi的硅包合物，在5 mA g的电流密度下观察到高达499 mAh g的可逆容量，对应于≈1.18个锂原子/硅原子。这些结果表明，硅包合物有望成为耐用的锂离子电池负极材料。
