Correlation between properties of various carbon defects and electrochemical charge carrier storage mechanisms for use in Li- and Na-based rechargeable batteries

With the growing interest in promising energy sources for high-energy-demand devices, the development of materials for use in rechargeable batteries based on electrochemical charge carrier storage, such as Li and Na, has attracted intensive attention. Among them, carbon materials (e.g., graphene, graphite, and disordered carbons) have been extensively used as electrode materials for battery systems because of their critical advantages, namely, relatively good charge carrier storage capability, low cost, abundant resources, and simple manufacturing process. In particular, various types of defects are indispensably formed in the carbon structure during the manufacturing processes, which significantly influence their electrochemical charge carrier storage mechanisms and thus determine the electrochemical properties of the carbon-based rechargeable battery systems. This comprehensive review summarizes the correlation between the fundamental properties of carbon defects and electrochemical Li and Na storage mechanisms for Li- and Na-based rechargeable batteries, representative cations using battery systems, with a special focus on atomic-scale science and technology, which have a notable role in investigating and understanding the interaction between the defect phases and charge carriers in carbon structures. First, various carbon defects are categorized for the purpose of this work; then, computational/experimental methods for analyzing them and their critical properties (especially electronic structure) are introduced because identifying defect types is critical. Next, the roles and influences of carbon defects on electrochemical charge carrier storage mechanisms (especially adsorption and intercalation [insertion], diffusion, and formation of metal clusters) are described for Li- and Na-based rechargeable batteries. This study focuses on the physicochemical and electrochemical properties, which are key characteristics of carbon defects that determine their optimal utilization in rechargeable battery systems.