High-Entropy Li-Rich Layered Cathodes with Negligible Voltage Decay through Migration Retardation Effect

The development of advanced Li- and Mn-rich layered cathodes (LRO) is essential for high-energy lithium-ion batteries (LIBs). However, LRO exhibits large voltage hysteresis and rapid voltage decay with irreversible TM migration upon prolonged cycling. Given that high-entropy oxides have expanded the potential for retarding the harmful phase transition and regulating the site energies, therefore a high-entropy Li_1.17Mn_0.50Ni_0.12Co_0.12Mg_0.03Cu_0.02Ti_0.02Nb_0.02O₂ cathode is synthesized (HELRO) for LIBs in the present study, demonstrated significantly improved voltage retention and energy output. In addition, this work unveils the sluggish degradation of superlattice and local structure in HELRO during long charge-discharge cycles and explains the "migration retardation effect." The higher configurational entropy contributes to the higher energy barriers for in-plane, out-of-plane, and continuous Mn migrations due to the synergistic ionic-covalent enhancement of Mn─O bonds. This work provides new insights for understanding the improvement mechanisms of high entropy cathodes and demonstrates the feasibility of suppressing long-standing voltage decay by high entropy design combining covalent and ionic elements.