Systematic study of grain size model for the electrochemical performance of Co3O4 anode

Abstract

Along with the expansion of the proportion of renewable energy due to environmental pollution, the demand for eco-friendly electric vehicles and energy storage system to compensate for the shortcomings of renewable energy continues to grow. In addition, the growing market for portable electronic devices such as smartphones and tablets has also significantly increased the importance of secondary batteries, a key device. In order to meet the growing demand for secondary batteries and to make more useful use of limited resources, it is necessary to increase the energy density and life span of secondary batteries. Graphite, commonly used anode material, is charged with intercalation/deintercalation reaction with lithium ions between layers and has a relatively low theoretical capacity of about 372 mAhg$^{-1}$, while substances such as metal oxides, sulfides, phosphides, silicon, and tin have a very high electrical capacity because they are charged through alloying reaction or conversion reaction that directly react with lithium ions. Among them, cobalt oxide (Co$_3$O$_4$) is a highly promising candidate for anode material not only chemically stable but also with a high theoretical capacity of 890 mAhg$^{-1}$. The Co$_3$O$_4$ presented in this study is the anode material with excellent performance that has both the advantages of nanoscale particles with short diffusion length and good electrical conductivity and micro-size particles with high tap-density. However, it has been confirmed that the electrochemical performance of this material varies depending on the grain size of the particles, such as rate capability and cycle stability. In this study, electrochemical performance of electrode materials with different grain sizes is measured, and various analyses are used to determine the cause of this phenomenon.