High-Entropy Approach vs. Traditional Doping Strategy for Layered Oxide Cathodes in Alkali-Metal-Ion Batteries: A Comparative Study

The traditional doping strategy has emerged as an effective method for addressing challenges such as irreversible phase transitions and poor cycling stability in transition metal layered oxides (TMLOs), making them promising cathode materials for alkali-ion batteries (AIBs). Recently, high-entropy approaches, a new class of modification strategies, have been gaining increasing attention. While these two methods – doping strategy and high-entropy – demonstrate some similarities, they also exhibit distinct differences. However, a systematic review of these approaches has not been performed yet, and their unique electrochemical outcomes are often confused. Herein, we present a comparative analysis and systematic discussion of the traditional doping strategy and the innovative high-entropy approaches. Using layered oxide cathodes as specific examples, we initially explore the effects of single-atom doping at various sites and the synergistic effects of multi-atom doping. Subsequently, we highlight five unique effects of materials modified through the high-entropy approaches: structure stabilization, high disorder characteristics, the entropy extension effect, cocktail effect and entropy-enhanced local regulation. These properties significantly enhance battery cycling performance, distinguishing the high-entropy method from the conventional doping. We also summarized its application in AIBs. Finally, a summary and outlook are provided, offering insights for the design and optimization of next-generation layered oxide cathode materials.