A comprehensive review of Li4Ti5O12-based electrodes for lithium-ion batteries: The latest advancements and future perspectives

Advanced electrical energy storage technology is a game changer for a clean, sustainable, and secure energy future because efficient utilization of newable energy hinges on cost-effect and efficient energy storage. Further, the viability of many emerging technologies depends on breakthroughs in energy storage technologies, including electric vehicles (EVs) or hybrid electric vehicles (HEVs) and smart grids. Lithium-ion batteries (LIBs), a great success in the portable electronics sector, are believed also the most promising power sources for emerging technologies such as EVs and smart grids. To date, however, the existing LIBs (with LiCoOx cathode and graphite anode) are still unable to meet the strict requirements for safety, cycling stability, and rate capability. The development of advanced anode materials, which can overcome the shortcomings of graphite anode (such as formation of dendritic lithium during charge and undesirable solid electrolyte interface), is of critical importance to enhancing the cycling stability and operational safety of LIBs. Lithium titanate (Li4Ti5O12) has recently attracted considerable attentions as a potential anode material of LIBs for high power applications due to several outstanding features, including a flat charge/discharge plateaus (around 1.55 V vs. Li/Li+) because of the two-phase lithium insertion/extraction mechanism and minimum chance for the formation of SEI and dendritic lithium, dramatically enhance the potential for high rate capability and safety. In addition, there is almost no volume change during the lithium insertion and extraction processes, ensuring a high cycling stability and long operational life. However, the electronic conductivity of Li4Ti5O12 is relatively low, resulting in large polarization lose, more so at higher cycling rates, and poor rate performance. Currently, considerable research efforts have been devoted to improving the performance of Li4Ti5O12 at fast charge/discharge rates, and some important progresses have been made. In this review, we first present a general overview of the structural features, thermodynamic properties, transport properties, and the electrochemical behavior of Li4Ti5O12 under typical battery operating conditions. We then provide a comprehensive review of the recent advancements made in characterization, modification, and applications of Li4Ti5O12 electrodes to LIBs, including nanostructuring, surface coating, morphological optimization, doping, and rational design of composite electrodes. Finally, we highlight the critical challenges facing us today and future perspectives for further development of Li4Ti5O12-based electrodes. It is hoped that this review may provide some useful guidelines for rational design of better electrodes for advanced LIBs. (C) 2015 Elsevier B.V. All rights reserved.