Exploring the Relationship between the Entropy Effect and Element Effect in High-Performance High-Entropy Materials

High-entropy materials show significant potential in various fields. It is commonly recognized that the entropy stabilization effect and the element synergy effect jointly affect high-entropy materials. However, the debate yet persists over whether the entropy stabilized effect or element synergy dominates their performance. Herein, high-entropy anode materials with entropy values ranging from 1.09 to 1.61 R have been designed, proposing the concept of a critical high entropy value (CEA, 1.5 R), unexpectedly discovering that material properties undergo significant optimization as entropy increases when the configurational entropy is lower than the CEA, but when it exceeds the CEA, the element synergy effect gradually emerges due to the marginal effect of the entropy stabilization effect, which deliver excellent electrochemical performances for the lithium-ion capacitors (LICs) anode. Assembling it with an activated carbon (AC) cathode for LICs, high energy density (193 Wh kg–1) and high power density (10 kW kg–1) can be achieved. Impressively, benefiting from the real high-entropy effect and element effect, the as-obtained materials with 1.6 R deliver highly reversible lithium storage behavior, enhanced mechanical properties postlithium insertion, and a thinner and more stable SEI according to TOF-SIMS and XAFS results. These explorations have extensive guiding implications for the design and fabrication of high-entropy materials with superior performance.