Tuning the structure and property of nanostructured cathode materials of lithium ion and lithium sulfur batteries

A great deal of progresses has been made in the pursuit of high energy and high power battery devices in the past decades on account of the growing demand for clean and sustainable energy. The tremendous challenges in increasing the specific energy and power density of batteries lie mainly in the cathode materials. Lots of attempts have been made to improve the reversible capacity and rate capability of cathode materials for lithium ion batteries in the past few years. On the one hand, the rate capability of the cathode materials depends strongly on their surface structures, which determine the kinetics of lithium ion transportation and intercalation. Through tuning the surface structure of cathode materials, the density of channels for fast Li+ diffusion can be increased, and therefore enhance greatly the surface/interfacial transportation kinetics of lithium ions. On the other hand, the reversible capacity of the cathode materials of lithium ion batteries is in direct proportion to the number of electrons transferred, thus exploration of high capacity cathode materials beyond intercalation, such as sulfur cathodes, has been conducted extensively. The utilization efficiency of sulfur active materials, the reaction kinetics and trapping of soluble polysulfides depend also on the structure of sulfur cathodes. This review outlines recent developments in structure-tuning of the most appealing cathode materials, including layered lithium metal oxides, olivine structured LiFePO4, spinel LiMn2O4 and LiNi0.5Mn1.5O4, as well as sulfur cathodes. The structure-dependent properties of the cathode materials are summarized, mainly focusing on electrochemical performance, which can provide an in-depth understanding and rational design of high performance cathode materials. Further direction and perspectives of research in the present field are also addressed.