Quasi-Intercalation Compounds Boost Battery Performance

Inserting lithium ions between the atomic layers in ZnSb and related materials leads to less disruptive crystal lattice changes than those experienced by conventional intercalation compounds such as graphite, according to a study by Cheol-Min Park and Hun-Joon Sohn of Seoul National University, in South Korea (Adv. Mater., DOI: 10.1002/adma.200901427). These new quasi-intercalation compounds can be lithi­ated reversibly in a way that is electrochemically beneficial in terms of reaction energy and kinetics, which establishes them as potential anode materials for rechargeable lithium-ion batteries. The team identified ZnSb, black phosphorus, and gray arsenic as examples of such compounds, explaining that these materials can readily be quasi-intercalated with lithium as a result of their accommodating layered and puckered structures. In tests of ZnSb's potential as a battery anode material, the group prepared electrodes by using a high-energy milling method to evenly distribute nanocrystals of ZnSb in amorphous carbon. The test material outperformed commercial graphite electrodes in terms of charge capacity under various conditions and retained nearly 90% of its initial charge capacity throughout 200 charge-discharge cycles, the researchers report.