Bucher Nicolas, Hartung Steffen, Nagasubramanian Arun, Cheah Yan Ling, Hoster Harry E, Madhavi Srinivasan
TUM CRREATE, Singapore 138602, Singapore.
ACS Appl Mater Interfaces. 2014 Jun 11;6(11):8059-65. doi: 10.1021/am406009t. Epub 2014 May 28.
Due to its potential cost advantage, sodium ion batteries could become a commercial alternative to lithium ion batteries. One promising cathode material for this type of battery is layered sodium manganese oxide. In this investigation we report on the influence of morphology on cycle performance for the layered NaxMnO2+z. Hollow spheres of NaxMnO2+z with a diameter of ∼5 μm were compared to flake-like NaxMnO2+z. It was found that the electrochemical behavior of both materials as measured by cyclic voltammetry is comparable. However, the cycle stability of the spheres is significantly higher, with 94 mA h g(-1) discharge capacity after 100 cycles, as opposed to 73 mA h g(-1) for the flakes (50 mA g(-1)). The better stability can potentially be attributed to better accommodation of volume changes of the material due to its spherical morphology, better contact with the added conductive carbon, and higher electrode/electrolyte interface owing to better wetting of the active material with the electrolyte.
由于其潜在的成本优势，钠离子电池可能成为锂离子电池的商业替代品。这种类型电池的一种有前景的阴极材料是层状钠锰氧化物。在本研究中，我们报告了形态对层状NaxMnO2+z循环性能的影响。将直径约为5μm的NaxMnO2+z空心球与片状NaxMnO2+z进行了比较。结果发现，通过循环伏安法测量，两种材料的电化学行为具有可比性。然而，球体的循环稳定性明显更高，100次循环后放电容量为94 mA h g(-1)，而片状材料为73 mA h g(-1)(50 mA g(-1))。更好的稳定性可能归因于其球形形态使材料体积变化得到更好的调节、与添加的导电碳有更好的接触以及由于活性材料与电解质的更好润湿性而具有更高的电极/电解质界面。
