Recent advances and prospects of single-crystal cathode materials

The development of lithium-ion battery cathode materials with higher energy density and longer cycle life is critical for advanced energy storage systems. Layered oxides are promising candidates due to their high theoretical capacity, superior cycling stability, and cost-effectiveness. However, conventional polycrystalline cathodes exhibit severe performance degradation under prolonged cycling and high-voltage operation, necessitating innovative material design strategies. Single-crystal materials, characterized by their well-defined morphological features, demonstrate distinct advantages including enhanced mechanical stability, low surface area, reduced grain boundary density, and exceptional cycling stability, effectively suppressing crack propagation and parasitic side reactions during electrochemical cycling. Nevertheless, challenges persist in single-crystal systems, including limited lithium-ion diffusion kinetics and intragranular crack formation. This review systematically summarizes the characteristics of single-crystal materials from four key aspects: synthesis methodologies, morphological control, electrochemical performance advantages, and modification strategies, establishing fundamental principles for rational material design. This work further extends the discussion to Na-ion battery systems, demonstrating the universal applicability of single-crystal engineering across battery chemistries. Finally, we outline future research directions for engineering high-performance single-crystal cathode materials, providing actionable insights for next-generation energy storage systems.