Present LIB Chemistries

Abstract

Abstract Typical materials used in commercial lithium‐ion batteries and their chemistries are focused in this article. Materials for positive and negative electrodes and electrolytes are separately discussed, paying attention on reactions between them. Selected new trends of these materials are also shortly added. Several lithium‐containing (lithiated) compounds are introduced as the positive‐electrode active materials for present lithium‐ion batteries (LIBs), such as LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiFePO 4 , and their derivatives. The properties of these materials are presented, including crystal structures, potential, capacity, rate capability, safety, and cost. Technologies applied to these materials for various applications are also shown. Carbonaceous materials, lithium titanate, and silicon‐based materials have been employed as negative electrodes for LIBs. In particular, graphite has played a main role as a negative‐electrode material for 25 years. This is principally because of its high capacity, low potential, low cost, etc. Recently, small amounts of silicon‐based materials are mixed with graphite to enhance the volumetric energy density of LIBs. In addition, high‐potential negative electrode of lithium titanate has also been used since little electrolyte decomposition takes place, resulting in the long cycle lives of LIBs. These commercialized negative electrodes are discussed. Electrolyte systems that have been proposed for and practically used in LIBs are surveyed. Those are categorized into several groups and their compositions and physicochemical properties are separately described. Each electrolyte system group has its own advantages and disadvantages as the LIB electrolytes. Contributions of the electrolyte composition to the battery performances are briefly discussed.