Enhancing Sodium Ion Battery Performance through Biphasic Layered Oxide Cathodes

Biphasic layered cathodes represent a strategic advancement in overcoming the inherent limitations of single-phase materials by synergistically integrating distinct phase characteristics. Among these, the P2/O3 biphasic cathode stands out due to its integration of the rapid diffusion kinetics of the P2 phase with the high capacity of the O3 phase, resulting in superior battery performance. Given the critical role of phase ratio in determining the performance of biphasic cathodes, this work systematically examines the influence of synthesis methods, sintering temperatures, and sodium and dopant compositions on phase modulation. A comprehensive analysis of the kinetic and thermodynamic properties of the P2/O3 cathode is conducted, with findings correlated to electrochemical data to elucidate how thermodynamic stability and efficient diffusion kinetics contribute to enhanced functionality. Finally, a brief overview of other biphasic cathodes is provided, comparing their distinctive properties relative to those of the P2/O3 system.